Ag base alloy thin film and sputtering target for forming Ag base alloy thin film

ABSTRACT

The present invention relates to an Ag alloy film. Particularly, it is preferably used as a reflective film or semi-transmissive reflective film for an optical information recording medium having high thermal conductivity/high reflectance/high durability in the field of optical information recording media, an electromagnetic-shielding film excellent in Ag aggregation resistance, and an optical reflective film on the back of a reflection type liquid crystal display device, or the like. The Ag alloy film of the present invention comprises an Ag base alloy containing Bi and/or Sb in a total amount of 0.005 to 10% (in terms of at %). Further, the present invention relates to a sputtering target used for the deposition of such an Ag alloy film.

This application is a continuation of Ser. No. 11/313,815, filed Dec.22, 2005, now U.S. Pat. No. 7,419,711, which is a continuation of Ser.No. 10/633,550, filed Aug. 5, 2003, now U.S. Pat. No. 7,514,037.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an Ag alloy film. More particularly, itrelates to an Ag alloy film preferably used as a reflective film or asemi-transmissive reflective film for an optical information recordingmedium having high thermal conductivity/high reflectance/high durabilityin the field of optical information recording media, anelectromagnetic-shielding film excellent in Ag aggregation resistance,or an optical reflective film on the back of a reflection type liquidcrystal display device or the like. Further, the present inventionrelates to a sputtering target for use in deposition of such an Ag alloyfilm.

2. Description of the Related Art

For the reflective films or the semi-transmissive reflective filmsincluded in optical information recording media (optical disks), Au, Al,Ag, or alloys containing these as main components have been widely usedfrom the viewpoints of thermal conductivity, reflectance, anddurability.

The Ag-based reflective film containing Ag as a main component has thefollowing features: it has high reflectance with respect to a violetlaser for use in a next-generation optical disk, and high thermalconductivity required of a write-once/writable disk; and, in addition,the raw material cost thereof is lower as compared with an Au-basedreflective film. Therefore, it is a promising material as a reflectivefilm or a semi-transmissive reflective film. However, it is superior toan Al-based reflective film in terms of durability, but it does not havedurability as high as that of the Au-based reflective film. In order toput it into actual use as a reflective film or a semi-transmissivereflective film of an optical disk, it is necessary to improve thedurability without impairing the high reflectance and the high thermalconductivity inherently possessed by Ag.

As for the means for improving the durability of such an Ag-basedreflective film, the following improvement measures have been reported.For example, the durability (chemical stability) is respectivelyimproved by adding Au, Pd, Cu, Rh, Ru, Os, Ir, and Pt to Ag in U.S. Pat.No. 6,007,889, or by adding Pd and Cu to Ag in U.S. Pat. No. 5,948,497.Further, the present inventors also have proposed a method in which thedurability (thermal stability in the inhibition of grain growth, or thelike) is improved by adding rare earth metal elements to Ag in JP-A15464/2002.

However, for high-speed recording DVDs or next-generation optical disks,the levels of characteristics required of the reflective film have beenfurther raised. This results in demands for durability, thermalconductivity, and reflectance of higher levels than ever before.

Particularly, for the durability, there is a demand for high corrosionresistance against halogen elements including chlorine. This demand isparticularly prominent for a write-once optical disk in which a halogenelement-containing organic dye recording film, a protective film, anadhesive layer, and the like are directly stacked on a reflective film.Further, as distinct from a DVD, the next-generation optical disk is inan inverted stacked configuration obtained in the following manner.First, a reflective film is deposited on a transparent plasticsubstrate, and dielectric protective film/recording film/dielectricprotective film/are stacked and deposited thereon. For this reason, thesurface roughness of the reflective film must be extremely reduced inorder to suppress the deterioration of the recording and reproductioncharacteristics. Further, the next-generation optical disk is requiredto be capable of keeping the stability of the surface roughness evenwhen put under a thermal load.

Whereas, as for the thermal conductivity, the heat generated in the verysmall region of the recording film through laser light irradiation isrequired to be rapidly diffused. Thus, in order for the reflective filmto also have the function as a thermal diffusion film, the film isrequired to have high thermal conductivity.

Further, as for the reflectance, the reflective film is required to havehigh reflectance also with respect to the violet laser for use in ahigh-speed DVD or a next-generation optical disk.

However, no Ag base alloy has been yet found which satisfies all theserequirements. In order that the reflective film may ensure highreliability as being used for a high-speed DVD or a next-generationoptical disk, there is a strong demand for an Ag base alloy which hasall the required characteristics of high thermal conductivity, highreflectance, and high durability.

On the other hand, conventionally, an Ag film has found various usesbecause of its high visible light transmittance and excellent infraredshielding property. For example, an infrared-shielding Ag filmtransparent member obtained by forming Ag on a transparent substrate ofglass or the like through sputtering or the like is used in order toimprove the heating and cooling efficiency in a room. Further, since theAg film is also excellent in radio wave shielding property, for example,in order to protect electronic equipments which may undergomis-operation due to radio wave from an external radio wave, or in orderto suppress the emission of the radio wave generated from electronicequipments, it is used in the following manner. An Ag film is applied asdescribed above on the window pane of the laboratory in which theequipments are set; or an Ag film or an Ag film-applied substrate ismounted internally in or externally on each of the equipments.

However, the Ag film has low abrasion resistance, and further, it hasinsufficient durability against environment. Therefore, it will bedeteriorated due to moisture or the like, and hence it is difficult touse for a long period. For this reason, a means of increasing thethickness of the Ag film has been adopted. However, a sufficientsolution has not yet been made from the viewpoints of abrasionresistance and durability improvements. Eventually, the Ag film will bedeteriorated with the passage of time, so that the pure Ag film lacksthe practicality. Incidentally, through the increase in film thickness,the electromagnetic shielding characteristics (infrared shieldingproperty and radio wave shielding property) are improved. However, thevisible light transmittance is decreased, so that it becomes dark in theroom.

Under such circumstances, as a technique for increasing thetransmittance within a visible light region, and further, improving theabrasion resistance and the weather resistance of the Ag film, there isproposed a technique of coating the Ag film with a transparentdielectric film made of an oxide such as tin oxide, zinc oxide, ortitanium oxide, or a nitride such as silicon nitride. Further, in orderto improve the adhesion between the Ag film and the oxide or thenitride, there is also proposed a technique of inserting Cr or a Ni—Cralloy layer between the Ag film and the oxide or the nitride.

In accordance with the technique, it is possible to reduce the opticalreflectance of the Ag film. This produces the effects of allowing thereduction of the glaring feeling due to a reflected light from the Agfilm, and providing a longer life period than that of the pure Ag film.However, even if Ag is coated with a transparent dielectric film, Agaggregates from the defective portions such as pinholes and scratches ofthe transparent dielectric film itself as the starting points whenexposed to air. As a result, the Ag film tends to undergo film breaking(i.e., break in the continuity of the film), so that film breakingoccurs (the continuity of the film is broken) In such a case, theconductivity of the Ag film is lost, resulting in a remarkable reductionin electromagnetic shielding characteristics. Further, unlimited numberof white points occur due to the aggregation on the Ag film-appliedsubstrate surface of glass, film, or the like, resulting in reductionsof designability and salability.

As techniques for improving the aggregation of such an Ag film, varioustechniques have been proposed. For example, in JP-A No. 315874/1995,there is proposed a heat ray-shielding glass obtained by forming a metalthin film prepared by adding at least one element selected from thegroup consisting of Pd, Pt, Sn, Zn, In, Cr, Ti, Si, Zr, Nb, and Ta in anamount of 5 to 20 mol % to Ag on the surface of a glass plate.

Whereas, in JP-A No. 293379/1996, there is proposed a technique forstacking a metal layer containing Ag as a main component, and Pd in anamount of 0.5 to 5 at % based on the amount of Ag, and transparentdielectric layers each containing one or more metal oxides selected fromthe group consisting of Zn, In, and Sn on a substrate in such a mannerthat the metal layer is sandwiched between the transparent dielectriclayers.

Further, in JP-A No. 135096/1997, there is proposed anelectromagnetic-shielding substrate obtained by adding one or moreelements selected from the group consisting of Pb, Cu, Au, Ni, Zn, Cd,Mg, and Al in an amount of 3 at % to Ag. Whereas, in JP-A No.231122/1999, there is disclosed a technique for attaining theimprovement of the aggregation resistance of Ag by adding Pb, Cu, Au,Ni, Pd, Pt, Zn, Cd, Mg, and Al to Ag.

Still further, the present inventors have proposed a technique forattaining the improvement of the aggregation resistance of Ag by addingSc, Y, and rare earth elements to Ag (JP-B No. 351572/2001).

Even with the proposals or the proposed Ag alloy films, the aggregationof Ag proceeds with passage of time, resulting in deterioration of theAg alloy films. For this reason, for example, when the film is used withits surface coated with each of the Ag alloy films exposed to air, theaggregation of Ag occurs centering on the defective portions of thetransparent film covering the Ag alloy film. Therefore, the result isthat the film must be processed into a laminated glass or an insulatingglass for use so that the Ag alloy film surface is not exposed to air,leading to an increase in manufacturing cost. Further, also in the casewhere the film is processed into a laminated glass or an insulatingglass, white points occur unless it is processed into a laminated glassor an insulating glass immediately after Ag film formation. This resultsin a loss of the value in use as a commercially available product.Further, even in the case where it has been processed into a laminatedglass or an insulating glass, the resulting glass does not havesufficient durability because long-term use results in deterioration ofthe Ag alloy film.

Incidentally, in recent years, a reflection type liquid crystal displaydevice operating with a small power consumption because a lamp is notrequired to be included therein has received attention. An opticalreflective film is essentially disposed as a reflector on the back ofthe reflection type liquid crystal display device. It reflects indoorlight, natural light, or the like, and serves as a light source forimage formation. For this reason, the higher the reflectance of theoptical reflective film is, the brighter and the easier to see theformed image is.

Conventionally, a thin film of Al with a high reflectance has been usedas the optical reflective film. However, in recent years, a thin filmcomposed almost exclusively of Ag (Ag thin film) which has higherreflectance, and is also resistant to chemical corrosion has come intouse as the optical reflective film.

However, in the case where the Ag thin film has been exposed into airfor a long time under high temperatures during manufacturing of a liquidcrystal display device, in the case where it has been exposed under hightemperatures and high humidities for a long time during use aftermanufacturing, or in other cases, white turbidity and white pointscaused by the increase in size of crystal grains, the aggregation of Agatoms, the oxidation of Ag, or the like occur, resulting in a decreasein reflectance. For this reason, it has not been possible to obtain ahigh reflectance inherent in Ag. Further, the inevitable heat history(to 200° C.) during device manufacturing causes the crystal grain growthand the aggregation of Ag atoms, which involve the increase in roughnessof the thin film surface and the anomalous grain growth. This results ina difficulty in device formation, and a further reduction inreflectance.

Under such circumstances, a proposal has been made in which differentkinds of elements are added to Ag for the purpose of preventing thegrowth of crystal grains of Ag and the aggregation of Ag atoms, andallowing high optical reflectance inherent in Ag to be exerted and kept.

For example, in JP-A No. 134300/1995, there is disclosed a thin filmmade of a metal which is more susceptible to oxidation than silver,specifically, a silver alloy (Ag base alloy) containing one, or two ormore metals selected from the group consisting of magnesium, aluminum,titanium, zirconium, and hafnium.

Whereas, in JP-A No. 230806/1997, there is disclosed a thin film made ofa silver-based metal material (Ag base alloy) which is an alloy withdifferent kinds of elements for preventing the migration of silverelement, specifically, one, or two or more kinds of metals selected fromthe group consisting of aluminum, copper, nickel, cadmium, gold, zinc,and magnesium.

However, even with the forgoing prior-art techniques, it has not beenpossible to sufficiently suppress the growth of crystal grains of Ag andthe aggregation of Ag atoms. Accordingly, it has not been possible toensure high optical reflectance inherent in Ag.

SUMMARY OF THE INVENTION

In view of the foregoing circumstances, the present invention has beencompleted. It is therefore a first object of the present invention toprovide an Ag base alloy reflective film or semi-transmissive reflectivefilm for an optical information recording medium having high reliabilityas use for a high-speed DVD or a next-generation optical disk, and anoptical information recording medium including the reflective film orthe semi-transmissive reflective film by finding an Ag base alloy havinghigher thermal conductivity/higher reflectance/higher durability thanthose of pure Ag or conventional Ag alloys.

It is a second object of the present invention to provide anelectromagnetic-shielding Ag alloy film which is less likely to undergoaggregation of Ag, and therefore has excellent durability, and anelectromagnetic-shielding Ag alloy film-formed product.

It is a third object of the present invention to provide ahigh-performance optical reflective film having high optical reflectancealmost equal to the high optical reflectance inherent in Ag, and aliquid crystal display device using the optical reflective film byfinding an Ag base alloy capable of preventing the growth of crystalgrains of Ag and the aggregation of Ag atoms as much as possible.

It is a fourth object of the present invention to provide a sputteringtarget usable for deposition of the foregoing various Ag alloy films.

The Ag base alloy thin film of the present invention, which attains anyobject described above, contains at least one element selected from thegroup consisting of Bi and Sb, and has a total content of Bi and Sb of0.005 to 10 atom % (at %, hereinafter). In this Ag base alloy thin film,the thickness of the Ag base alloy thin film is preferably set at 3 to300 nm. Whereas, the Ag base alloy thin film preferably furthercomprises at least one of rare earth metal elements. The rare earthmetal element is preferably at least one of Nd and Y.

When a thin film comprises an Ag base alloy having a total content of Biand Sb of 0.005 to 0.40 at %, the Ag base alloy thin film has all ofhigh thermal conductivity/high reflectance/high durability, and attainsthe first object. Herein, it is preferable that the Ag base alloyfurther comprises at least one selected from the group consisting of Ndand Y, and that the total content of the elements of the group is 0.1 to2 at %. Whereas, it is preferable that the Ag base alloy furthercomprises at least one selected from the group consisting of Cu, Au, Rh,Pd, and Pt, and that the total content of the elements of the group is0.1 to 3 at %.

When a thin film comprises an Ag base alloy having a total content of Biand Sb of 0.01 to 10 at %, the Ag base alloy thin film is less likely toundergo aggregation of Ag, and therefore has excellent durability, andattains the second object. Herein, it is preferable that the Ag basealloy further comprises at least one element selected from the groupconsisting of Cu, Au, Pd, Rh, Ru, Ir, and Pt, and that the total contentof the elements of the group is 0.3 at % or more.

When a thin film comprises an Ag base alloy having a total content of Biand Sb of 0.01 to 4 at %, the Ag base alloy thin film is capable ofpreventing the growth of crystal grains of Ag and the aggregation of Agatoms as much as possible, as well as has high optical reflectanceroughly equal to the high optical reflectance inherent in Ag, andattains the third object. Herein, it is preferable that the Ag basealloy further comprises rare earth metal elements in an amount of 0.01to 2 at %, and that the rare earth metal element is at least one of Ndand Y.

A sputtering target for forming an Ag base alloy thin film of thepresent invention, which attains the foregoing objects, comprises atleast one of Bi: 0.05 to 23 at % and Sb: 0.005 to 10 at %.

When the sputtering target for forming an Ag base alloy thin filmcomprises Bi in an amount of 0.05 to 4.5 at % or Sb in an amount of0.005 to 0.40 at %, it is suitable for deposition of the Ag base alloythin film having all of high thermal conductivity/high reflectance/highdurability.

When at least one of Bi: 0.2 to 23 at % and Sb: 0.01 to 10 at % issatisfied in terms of the content in the sputtering target, and the Bicontent and the Sb content in the sputtering target satisfy thefollowing formula (1), the sputtering target is suitable for depositionof the Ag base alloy thin film which is less likely to undergoaggregation of Ag, and therefore has excellent durability:0.01 at %≦0.000502x ³+0.00987x ²+0.0553x+y≦10 at %  Formula (1)

where, in the formula (1), x denotes the Bi content (at %) in the Agalloy sputtering target, and y denotes the Sb content (at %) in the Agalloy sputtering target; and at % denotes at %. Whereas, it ispreferable that the sputtering target further comprises at least oneelement selected from Cu, Au, Pd, Rh, Ru, Ir, and Pt in an amount of 0.3at % or more.

When at least one of Bi: 0.2 to 15 at % and Sb: 0.01 to 4 at % issatisfied in terms of the content in the sputtering target, and the Bicontent and the Sb content in the sputtering target satisfy thefollowing formula (2), the sputtering target is suitable for depositionof the Ag base alloy thin film which is capable of preventing the growthof crystal grains of Ag and the aggregation of Ag atoms as much aspossible, as well as has high optical reflectance roughly equal to thehigh optical reflectance inherent in Ag0.01 at %≦0.000502x ³+0.00987x ²+0.0553x+y≦4 at %  Formula (2)

where, in the formula (2), x denotes the Bi content (at %) in the Agalloy sputtering target, and y denotes the Sb content (at %) in the Agalloy sputtering target; and at % denotes at %.

The Ag base alloy thin film having a total content of Bi and Sb of 0.005to 0.40 at % is preferably used as a reflective film or asemi-transmissive reflective film for an optical information recordingmedium.

The Ag base alloy thin film having a total content of Bi and Sb of 0.01to 10 at % is preferably used as an electromagnetic-shielding film. Theelectromagnetic-shielding film preferably has a layer in which at leastone content of Bi and Sb is higher than inside the Ag base alloy thinfilm on at least one of the surface and the interface of the Ag basealloy thin film. Further, in the electromagnetic-shielding film, thelayer in which at least one content of Bi and Sb is higher contains atleast one of oxidized Bi and oxidized Sb.

The Ag base alloy thin film having a total content of Bi and Sb of 0.01to 10 at % is also preferably used as an electromagnetic-shieldingfilm-formed product. The electromagnetic-shielding film-formed productcan be configured such that a film containing at least one selected fromthe group consisting of oxide, nitride, and oxynitride is formed as anunderlayer on the substrate, the Ag base alloy thin film is formed onthe underlayer, and a film containing at least one selected from thegroup consisting of oxide, nitride, and oxynitride is formed as aprotective film on the Ag base alloy thin film. Herein, it is preferablethat the underlayer and the protective layer are oxides or oxynitrides.Then, it is preferable that the oxide is at least one selected from thegroup consisting of ITO, zinc oxide, tin oxide, and indium oxide.Further, it is preferable that the thicknesses of the underlayer and theprotective layer are 10 nm or more and 1000 nm or less. Theelectromagnetic-shielding film-formed product is preferably configuredsuch that the substrate is a transparent substrate; a transparent memberis further stacked on the protective layer; or a transparent member isstacked on the protective layer via a spacer, and a space layer isdisposed between the protective layer and the transparent member. It ispreferable that, in the electromagnetic-shielding film-formed product,the thickness of the Ag base alloy thin film is 3 nm or more and 20 nmor less.

The Ag base alloy thin film having a total content of Bi and Sb of 0.01to 4 at % is preferably used as an optical reflective film for use as areflection electrode or a reflector of a liquid crystal display device.

If the Ag base alloy of the present invention is used as a reflectivefilm or a semi-transmissive film for an optical information recordingmedium, it becomes possible to significantly enhance the recording andreproduction characteristics and the reliability of the opticalinformation recording medium (particularly, a high speed DVD or anext-generation optical disk) because the film has high thermalconductivity/high reflectance/high durability. Whereas, the sputteringtarget for forming an Ag base alloy thin film of the present inventionis preferably used for the deposition of a reflective film or asemi-transmissive reflective film of the optical information recordingmedium. The reflective film or the semi-transmissive reflective filmdeposited using this is excellent in alloy composition, alloy elementdistribution, and in-plane uniformity of film thickness. In addition,the reflective film or the semi-transmissive reflective film has a lowcontent of impurity components, and hence it is favorably exploited toshow high performances (high thermal conductivity, high reflectance, andhigh durability) as a reflective film, which allows the production ofhigh-performance high-reliability optical information recording medium.Further, the optical information recording media having the reflectivefilm and the semi-transmissive reflective film becomes capable ofsignificantly enhance the recording and reproduction characteristics andthe reliability.

Whereas, if the Ag base alloy of the present invention is used as anelectromagnetic-shielding film, the aggregation of Ag is less likely tooccur, and therefore, the reduction in electromagnetic shieldingproperty, generation of white points, and the like, due to the loss ofconductivity caused by aggregation of Ag are less likely to occur. It ispossible to improve the durability in terms of such points. Thesputtering target for forming an Ag base alloy thin film of the presentinvention is preferably used for the deposition of an electromagneticshielding film.

Whereas, if the Ag base alloy of the present invention is used as anoptical reflective film, it is possible to provide a high-performanceoptical reflective film having high optical reflectance roughly equal tothe high optical reflectance inherent in Ag, and a liquid crystaldisplay device using the optical reflective film. The sputtering targetfor forming an Ag base alloy thin film of the present invention ispreferably used for the deposition of the optical reflective film ofsuch a liquid crystal display device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the results of the composition analysisalong the thickness of the film with X-ray photoelectron spectroscopy onan Ag—Bi alloy film, which shows the relationship between the sputteringtime and the composition in the X-ray photoelectron spectroscopy; and

FIG. 2 is a diagram showing the narrow-range spectrum measurementresults of Bi with X-ray photoelectron spectroscopy on an Ag—Bi alloyfilm, which shows the relationship between the bond energy and theintensity.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First, an embodiment of a first invention will be described.

The present inventors have conducted a close study under the foregoingproblems in order to provide an Ag base alloy reflective film orsemi-transmissive reflective film for an optical information recordingmedium having high thermal conductivity, high reflectance, and highdurability. As a result, they found that an Ag base alloy containing Biand/or Sb in a total amount of 0.005 to 0.40% has high reflectance andhigh thermal conductivity comparable to those of pure Ag, and is capableof exhibiting a higher level of durability than that of pure Ag, leadingto the completion of the present invention. Below, the present inventionwill be described in details.

An Ag base alloy reflective film or semi-transmissive reflective filmfor an optical information recording medium of the present inventioncomprises an Ag base alloy containing Bi and/or Sb in a total amount of0.005 to 0.40% as an essential element. Such a reflective film or asemi-transmissive reflective film comprising the Ag base alloy not onlyhas high thermal conductivity and high reflectance comparable to thoseof pure Ag, but also has excellent durabilities (thermal stability andchemical stability).

In general, a pure Ag thin film deposited by a sputtering process or thelike includes a large number of crystal defects (such as void,dislocation, and grain boundary). Ag atoms are readily diffused throughthe crystal defects. Therefore, when a pure Ag thin film is held under ahigh temperature high humidity environment, Ag atoms arediffused/aggregated at various sites, resulting in increases in surfaceroughness and crystal grain size. Whereas, also when put under anenvironment containing halogen ions such as chlorine ions, Ag atoms arereadily diffused/aggregated. The changes in thin film surface caused bysuch an aggregation entails a reduction in reflectance, which remarkablydeteriorates the recording and reproduction characteristics of anoptical disk. In particular, with a very thin semi-transmissivereflective film used for a DVD-ROM, the effect of aggregation exerted onthe reflectance is large, so that the reproduction characteristics of anoptical disk are remarkably deteriorated.

As the solving measures for the foregoing problems, alloying of Ag hasbeen studied so far. For example, alloying through the addition of anoble metal element (such as Au, Pd, or Pt) to Ag, or through theaddition of a rare earth metal element (such as Y), has been proposed.

If a noble metal element (such as Au, Pd, or Pt) is added to Ag foralloying, the aggregation of Ag atoms due to the effects of chlorineions, or the like is suppressed. However, it is not possible to suppressthe aggregation of Ag atoms due to holding under high temperatures andhigh humidities. Whereas, with a method in which a rare earth metalelement (such as Y) is added for alloying, the aggregation of Ag atomsdue to holding under high temperatures and high humidities issuppressed. However, it is not possible to suppress the aggregation ofAg atoms due to the effects of chlorine ions or the like. Namely, evenwith alloying using either of the element groups, it is not possible tosimultaneously suppress the aggregations of Ag atoms resulting from bothof holding under high temperatures and high humidities and the effectsof chlorine ions.

However, in accordance with the present invention, by adopting an Agbase alloy containing Bi and/or Sb in a total amount of 0.005% or more,it is possible to simultaneously suppress the aggregations of Ag atomsdue to holding under high temperatures and high humidities and theeffects of chlorine ions. Further, it has been shown that these elementsexhibit a more clear aggregation suppression effect with an increase inits content. However, the addition of such an element to Ag tends toreduce the thermal conductivity and the reflectance relative to the pureAg thin film. This tendency becomes more noticeable with an increase incontent of the element. This results in reductions in the thermalconductivity and the reflectance of the Ag base alloy thin film.

As for the content of the elements, the upper limit of the total contentcan be raised up to 3% from the viewpoint of ensuring high reflectancewith respect to a violet laser for use in a next-generation opticaldisk. However, if the total content exceeds 0.40%, it becomes impossibleto ensure high thermal conductivity required of the reflective film of ahigh-speed DVD or a next-generation optical disk. Therefore, the upperlimit of the total content has been set at 0.40% as the requirement forensuring both the characteristics of high reflectance and high thermalconductivity. On the other hand, if the total content is less than0.005%, the aggregation suppression effect through the addition of Biand/or Sb is not effectively exhibited. It is preferably 0.01% or moreand 0.3% or less, and more preferably 0.05% or more and 0.2% or less.Incidentally, in consideration of manufacturing of a sputtering target,or the like, Bi is preferably used from the viewpoint of excellenthandling.

In the present invention, for the purpose of further improving thedurability, particularly the thermal stability of an Ag base alloycontaining Bi and/or Sb, it is also effective to allow rare earth metalelements to be contained therein other than the foregoing elements.These elements have effects of further suppressing the aggregation of Agatoms due to holding under high temperatures and high humidities, andstill further enhancing the durability. As the rare earth metal element,Nd and/or Y is preferred. The content of these elements based on theamount of the Ag base alloy is preferably set at 0.1% or more and 2% orless in a total amount of Nd and/or Y. This is for the following reason:if the content is less than 0.1%, effective effects through the additionof the elements cannot be produced, and if the content exceeds 2%, highthermal conductivity cannot be obtained. The more preferred contentupper limit is 1%, and more preferably 0.5%.

Further, at least one selected from Cu, Au, Rh, Pd, and Pt may also beadded for the purpose of improving the durability, particularly thechemical stability of the Ag base alloy containing Bi and/or Sb. Theseelements have effects of further suppressing the aggregation of Ag atomsdue to the effects of chlorine ions, and still further enhancing thedurability. In order for the aggregation suppression effect of Ag atomsto be effectively exhibited, the total content is set at preferably 0.1%or more and 3% or less. The more preferred upper limit is 2%.

Whereas, in order to attain the further improvement of the chemicalstability of the Ag base alloy, it is also effective to add Mg, Ti, andZn in addition to the foregoing elements. The addition of these elementsproduces a lower durability improvement effect than with Au, Rh, Pd, andPt. However, it is useful for achieving a cost reduction of an opticaldisk because of its low raw material cost. Incidentally, Mg, Ti, and Znreduce the thermal conductivity and the reflectance with an increase incontent thereof. Therefore, the upper limit of the total content ofthese elements is set at 3%. As for the foregoing alloy element group,even addition of one kind can produce a sufficient effect. However, itis needless to say that it is possible to produce the same effect evenfor the addition of two or more kinds in combination. However, theforegoing effects obtainable through the addition of Nd and/or Y as arare earth metal element, and the foregoing effects obtainable throughthe addition of at least one selected from Cu, Au, Rh, Pd, and Pt arethe inherent effects observable for the Ag base alloy containing Biand/or Sb. For example, the same effects are not observable with pureAg.

As also disclosed in JP-A No. 184725/2001, there is known an Ag alloywhich has been improved in corrosion resistance by adding at least oneelement selected from Al, Au, Cu, Co, Ni, Ti, V, Mo, Mn, Pt, Si, Nb, Fe,Ta, Hf, Ga, Pd, Bi In, W, and Zr in an amount of 0.5 to 5% to Ag.However, Al, Au, Cu, Pt, and Pd do not have an effect of suppressing theaggregation of Ag atoms occurring when the Ag film has been held at hightemperatures. As a result, it is not possible to obtain the durabilityimprovement effect from the viewpoint of the thermal stability mentionedas the object in the present invention. Whereas, addition of Bi in anamount of 0.5% or more reduces the thermal conductivity, and hence it isnot preferred, and excluded from the present invention. Further, in JP-ANo. 92959/2002, there is disclosed an Ag alloy which has been improvedin chemical stability by adding Cu in an amount of 4 to 15 mass %, andAl, Zn, Cd, Sn, Sb, and Ir in an amount of 0.5 mass % or more to Ag.However, Cu, Al, Zn, Cd, Sn, and Ir do not produce an effect ofsuppressing the aggregation of Ag atoms due to holding under hightemperatures. Whereas, addition of Sb in an amount of 0.5 mass % (0.44%)or more reduces the thermal conductivity inherent in Ag, and hence it isnot preferred. Therefore, these known Ag alloys are distinctlydistinguished from the present invention in terms of the specificconstitution and functional effects.

The Ag base alloy reflective film and the Ag base alloysemi-transmissive reflective film for optical information recordingmedia of the present invention can be obtained by depositing the Ag basealloy of the foregoing alloy composition on a substrate with a vacuumdeposition process, an ion plating process, a sputtering process, or thelike. Out of these, the film deposited by a sputtering process isrecommendable. This is for the following reason. The Ag base alloyreflective film and the Ag base alloy semi-transmissive reflective filmdeposited by a sputtering process are superior in alloy elementdistribution and the in-plane uniformity of the film thickness to thefilms deposited by other deposition process. As a result, the film isfavorably exploited to show higher level of characteristics (highthermal conductivity, high reflectance, and high durability) as areflective film, which allows the production of high-performancehigh-reliability optical disk.

The Ag base alloy reflective film for an optical information recordingmedium in the present invention is a thin film for use as a reflectivefilm for single-layer recording for performing recording only on oneside of a disk, or the uppermost layer reflective film for multilayerrecording. The transmittance is almost 0%, and the reflectance isdefined by the constitution of the disk, and about 45% or more. Whereas,the film thickness may be appropriately determined in such a range as tomeet the foregoing reflectance and transmittance, and it may be normallyset at about 50 to 200 nm.

The semi-transmissive reflective film of the present invention is a filmfor use as a reflective film of a medium for performing two or moremultilayer recording on one side of a disk. Thetransmittance/reflectance are defined according to the configuration ofthe disk. The semi-transmissive reflective film denotes a thin filmhaving a transmittance of about 60 to 72% and a reflectance of about 18to 30%. Further, the thickness thereof may be appropriately determinedin such a range as to meet the foregoing reflection and transmittancerequirements, and it may be normally set at about 5 to 20 nm.

The Ag base alloy sputtering target for an optical information recordingmedium of the present invention can be manufactured by any method of adissolution/casting process, a powder sintering process, a spray formingprocess, and other processes. Out of these, manufacturing by a vacuumdissolution/casting process is recommendable. This is for the followingreason. The Ag base alloy sputtering target manufactured by the vacuumdissolution/casting process has a lower content of impurity componentssuch as nitrogen and oxygen than that of the one manufactured by otherprocess. As a result, the reflective film or the semi-transmissivereflective film deposited by using the sputtering target is effectivelyexploited to show high characteristics (high thermal conductivity, highreflectance, and high durability) as a reflective film, which allows theproduction of high-performance high-reliability optical disk.

The reflective film or the semi-transmissive reflective film of thepresent invention essentially contains Bi and/or Sb in an amount of0.005 to 0.40% as described above. In particular, in order to obtain athin film of a composition such that the Bi content falls within theforegoing range, Bi is required to be contained in an amount of about0.05 to 4.5% in the sputtering target.

For a thin film of a general alloy system such as Ag—Cu alloy system,Ag-noble metal alloy system, or Ag-rare earth metal alloy system, thecomposition of the sputtering target is roughly in agreement with thecomposition of the thin film. In contrast, when a thin film has beendeposited using a Bi-containing Ag base alloy sputtering target, the Bicontent in the thin film is reduced to several percent to several tensof percent of the Bi content in the sputtering target.

This is considered to be caused by the following: (1) Bi is revaporizedfrom the substrate side during film deposition because of the largedifference in melting point between Ag and Bi, or the higher vaporpressure of Bi than that of Ag; (2) Bi is difficult to sputter becausethe sputtering rate of Ag is higher than the sputtering rate of Bi;further (3) only Bi is oxidized on the sputtering target surface and isnot be sputtered because Bi is more susceptible to oxidation than Ag; orother factors. For these reasons, it is conceivable that the Bi contentin the thin film is reduced as compared with the Bi content in thesputtering target.

Therefore, the Bi content in the sputtering target in accordance withthe present invention is required to be set larger than each Bi contentin the objective reflective film and semi-transmissive reflective film.For example, in order to obtain a reflective film and asemi-transmissive reflective film each containing Bi in an amount of0.005 to 0.40%, the Bi content in the sputtering target may be set at0.05% or more and 4.5% or less, and preferably 0.1% or more and 3.6% orless in consideration of the content of Bi which will not beincorporated into the film.

The foregoing phenomenon is the phenomenon not observable for other Agbase alloys such as Ag—Sb alloy system and Ag-rare earth metal alloysystem. As for these Ag base alloys, the sputtering targets are roughlyin agreement in terms of composition with their respective thin filmsdeposited using these. Therefore, also in the present invention, forother elements than Bi, sputtering targets containing respectiveelements in such a range as to meet the foregoing requirements may bemanufactured.

The optical information recording medium of the present invention mayinclude the Ag base alloy reflective film or semi-transmissivereflective film of the present invention. There is no other particularrestriction on the constitution as the optical information recordingmedium. In the optical information recording medium field, all knownconstitutions are adoptable. For example, the optical informationrecording medium including the reflective film or semi-transmissivereflective film made of the foregoing Ag base alloy on one side of atransparent substrate of polycarbonate or the like has high reflectance,high thermal conductivity, and high durability. Therefore, as a matterof course, it can be used as a read-only, writing once, writable, orother type of optical information recording medium, as well as it canalso be preferably used for a high-speed DVD or a next-generationoptical disk.

Then, an embodiment of a second invention will be described.

The present invention is carried out, for example, in the followingmanner.

A sputtering target (an Ag alloy sputtering target for forming theelectromagnetic-shielding Ag alloy film in accordance with the presentinvention) is manufactured which comprises an Ag alloy containing atleast one of Bi: 0.2 to 23 at % and Sb: 0.01 to 10 at % (below, alsoreferred to as at %), and having a Bi content and a Sb contentsatisfying the following formula (2-1). By using the sputtering target,an Ag alloy film (the electromagnetic-shielding Ag alloy film inaccordance with the present invention) containing Bi and/or Sb in atotal amount of 0.01 to 10 at % is deposited on a substrate made of atransparent glass or the like by a sputtering process. As a result, itis possible to obtain an electromagnetic-shielding Ag alloy film-formedproduct in accordance with the present invention.0.01 at %≦0.000502x3+0.0987x2+0.0553x+Sb content≦10 at %  Formula (2-1)

Where, in the formula (2-1), x denotes the Bi content (at %) in thesputtering target (Ag alloy), and the Sb content denotes the Sb content(at %) in the sputtering target (Ag alloy); and at % denotes the samemeaning as atom %.

The present invention is carried out in this manner.

For attaining the foregoing objects of the present invention, thepresent inventors formed Ag alloy thin films of various compositions onsubstrates by a sputtering process using Ag base alloy sputteringtargets manufactured by adding various elements to Ag, and evaluated thethin films for the characteristics as the electromagnetic-shielding Agalloy films. As a result, they found as follows. By implementing an Agalloy film containing Bi and/or Sb, the migration of Ag is suppressed,so that aggregation becomes less likely to occur. This finding has ledto the completion of the present invention. Below, the details thereofwill be described.

“An Ag alloy film comprising an Ag base alloy containing Sc, Y, and oneor more elements of rare earth elements (JP-B No. 351572/2001)”previously invented by the present inventors has more excellent Agaggregation resistance as compared with a pure Ag film or an Ag alloyfilm comprising an Ag base alloy containing one or more elements of Pd,Pt, Sn, Zn, In, Cr, Ti, Si, Zr, Nb, and Ta. Therefore, it showscharacteristics excellent in durability (the Ag alloy film will not bedeteriorated even after long-term use) and weather resistance (Agaggregation resistance to a high-temperature high-humidity environment).

In contrast, the present inventors have found as follows. The Ag alloyfilm (the electromagnetic-shielding Ag alloy film comprising an Ag alloycontaining Bi and/or Sb in a total amount of 0.01 to 10 at %) inaccordance with the present invention is more excellent in effect ofsuppressing the aggregation of Ag, and exerts a sufficient effectthrough the addition of a tracer amount of them. In addition, it ispossible to still further reduce the electric resistance.

Further, the present inventors have found as follows. The foregoing “Agalloy film comprising an Ag base alloy containing Sc, Y, and one or moreelements of rare earth elements (JP-B No. 351572/2001)” is excellent indurability to oxygen and moisture in air. However, it cannot acquire asufficient resistance in an atmosphere containing a halogen element suchas salt water. In contrast, the Ag alloy film in accordance with thepresent invention also exhibits a sufficient resistance to salt water.

For the Ag alloy film in accordance with the present invention, byappropriately controlling the amount of additive elements (Bi and/or Sb)to be added, it is possible to obtain an Ag alloy film capable ofexerting the characteristics (i.e., infrared-shielding property andradio wave-shielding property) corresponding to the wavelength of anelectromagnetic wave. Incidentally, in the present invention, in thecase where the alloy film is mentioned as for infrared-shielding, itmeans that the alloy film has the shielding property against longwavelength (λ) of 8×10⁻⁷ m or more. Whereas, for the wavelength (λ) inthe case where the alloy film is mentioned as forelectromagnetic-shielding, it means that the alloy film has theshielding property against long wavelengths of 10⁻³ m or more.

As for the amounts (contents) of the additive elements (Bi and/or Sb),the total amount thereof is required to be set at 0.01 to 10 at %.

If Bi and/or Sb is added in a total amount of 0.01 at % or more, it ispossible to effectively inhibit the growth of crystal grains caused bythe surface diffusion of Ag. In particular, the Ag alloy film containingBi and/or Sb in a total amount of 0.05 at % or more is more excellent inchemical stabilities (particularly, weather resistance) than a pure Agfilm. Therefore, even if it is exposed under a high-temperaturehigh-humidity environment, the aggregation suppression effect of the Agalloy film is high, and the electromagnetic shielding property is alsovery excellent.

In particular, for a substrate made of an oxygen-containing compound, Biand/or Sb has a high affinity with oxygen, and hence it is diffused andconcentrated in the substrate interface, resulting in an improvement inadhesion. As a result, the aggregation of Ag is further reduced.Further, if the Ag alloy film surface is exposed to an atmosphere inwhich oxygen is present, Bi and/or Sb in the Ag alloy film is diffusedand concentrated in the surface of the Ag alloy film to form an oxidelayer (Bi and/or Sb oxide layer) The oxide layer cuts off the contactwith environment, so that the effect of suppressing aggregation of Ag isfurther enhanced.

FIGS. 1 and 2 respectively show the results of composition analysisalong the thickness of the film with XPS (X-ray photoelectronspectroscopy) of an Ag—Bi alloy film with a thickness of about 20 nmformed on a glass substrate (FIG. 1) and the narrow-range spectra of Bi(FIG. 2). As indicated, Bi is concentrated in the outermost surface.Further, the narrow-range spectra of Bi indicates that the concentratedBi in the outermost surface forms an oxide. On the other hand, thenarrow-range spectra of Bi according to XPS of the Ag—Bi alloy filminside after 1-minute, 2-minute, 3-minute, and 4-minute sputtering fromthe surface of the film provides peaks showing metal Bi. This indicatesthat only the outermost surface is oxidized. Further, the thickness ofthe oxide layer was analyzed with the RBS (Rutherford back scattering)analysis, and as a result, it was found to be a thickness of severalatomic layers. Whereas, also at the interface between the glasssubstrate and the Ag alloy film, the Bi composition is higher than thatof the Ag alloy film inside, and it is observable that Bi isconcentrated.

Bi and/or Sb is desirably contained in an amount of 0.05 at % or morefrom the viewpoint of densely forming the oxide layer of Bi and/or Sb,and cutting off the contact with environment. Namely, the lower limitvalue of the more preferred additive element (Bi and/or Sb) content is0.05 at %.

The upper limit value of the amount of the additive element (Bi and/orSb) to be added is set at 10 at % because the element addition effect issaturated, and the visible light transmittance may be reduced even ifthe amount added is increased. Incidentally, when the alloy film is usedas an infrared-shielding Ag alloy film, the upper limit value is set atdesirably 5 at % or less, further desirably 3 at % or less, and stillfurther desirably 1 at % or less. When the alloy film is used as anelectromagnetic-shielding Ag alloy film, the upper limit value isrecommendably set at 5 at % because the electric resistance of the Agalloy film increases with an increase in amount added, so thatsufficient electromagnetic shielding property may not be obtained. Themore preferred upper value is 3 at %, and the further preferred uppervalue is 1 at %. In particular, in order that an excellentelectromagnetic shielding property against long wavelengths of awavelength of 10⁻¹ m or more is exerted, the upper limit value isdesirably set at 5 at % to reduce the electric resistance. The morepreferred upper limit value is 3 at %, and the further preferred upperlimit value is 1 at %. Incidentally, the amount added (content) hereinmentioned is the composition of Bi and/or Sb relative to the whole Agalloy film including the concentrated layer of Bi and/or Sb.

The electromagnetic-shielding Ag alloy film in accordance with thepresent invention, as described above, contains Bi and/or Sb in a totalamount of 0.01 to 10 at %. In this case, if the film is configured so asto further contain at least one or more elements selected from Cu, Au,Pd, Rh, Ru, Ir, and Pt in an amount of 0.3 at % or more in addition tothese components, the chemical stability of Ag is further improved, andthe effect of suppressing the aggregation of Ag is more improved. Inparticular, these elements (Cu, Au, Pd, Rh, Ru, Ir, and Pt) show a lessdecrease in reflectance or electric resistance with an increase inamount added. Therefore, by adding these elements in a supplementarymanner, the Ag aggregation resisting effect becomes large. The amount ofthese elements (Cu, Au, Pd, Rh, Ru, Ir, and Pt) to be added is morepreferably 0.5 at % (at %) or more, and further preferably 0.8 at % ormore. On the other hand, the upper limit of the amount added has noparticular restriction. However, if it exceeds 10 at %, the elementaddition effect is saturated, as well as the visible light transmittanceis reduced, and the electric resistance is raised. This may make itimpossible to acquire a sufficient electromagnetic shielding property.Therefore, the upper limit of the amount of these elements (Cu, Au, Pd,Rh, Ru, Ir, and Pt) to be added is preferably set at 10 at %, morepreferably 8 at % or less, and further preferably 5 at % or less.Whereas, if rare earth elements such as Sc, Y, and Nd are added to theAg alloy film in accordance with the present invention, the aggregationproperty of Ag is further suppressed. The amount of these to be added ispreferably 0.1 at % or more, and further preferably 0.2 at % or more. Onthe other hand, the upper limit is preferably 1 at %, more preferably0.8% or less, and most preferably 0.6 at % or less from the viewpoint ofelectric resistance.

Further, other components than the foregoing components may also beadded in such a range as not to impair the function of the presentinvention according to the intended purpose. As such components, forexample, Ta, Co, Zn, Mg, Ti, and the like may be positively added.Incidentally, it does not matter that the impurities previously includedin the raw material are contained in the film.

The thickness of the electromagnetic-shielding Ag alloy film inaccordance with the present invention has no particular restriction. Itmay be appropriately changed according to the required characteristicssuch as electromagnetic shielding characteristic and visible lighttransmittance. It is preferably 3 nm or more and 20 nm or less. When itis less than 3 nm, the electromagnetic shielding characteristic may notbe satisfactorily obtainable. From such a viewpoint, the thickness ispreferably 5 nm or more, and further preferably 8 nm or more.Incidentally, when the film is used for radio wave-shielding, the filmthickness is preferably 5 nm or more, more preferably 8 nm or more, andfurther preferably 10 nm. Whereas, the film thickness is set atpreferably 20 nm or less, more preferably 18 nm or less, and furtherpreferably 15 nm or less, from the viewpoint of obtaining a sufficientvisible light transmittance.

In the present invention, in order to reduce the glaring feeling due toreflection of a visible light by the Ag alloy film, another film mayalso be formed other than the Ag alloy film. For example, an underlayermay also be disposed between the substrate and theelectromagnetic-shielding Ag alloy film. The underlayer to be formed onthe substrate has no particular restriction, but it preferably hastransparency from the viewpoint of visible light transmittance. Whereas,the underlayer may also be disposed for the purpose of improving theadhesion between the Ag alloy film and the substrate. Further, anunderlayer having conductivity is desirable because the heatray-shielding effect and the electromagnetic-shielding effect are alsoimproved. The underlayer of the composition having characteristicscorresponding to the intended purpose may be appropriately selected.

Examples of such an underlayer may include: oxide films each containingan oxide such as zinc oxide, tin oxide, titanium oxide, indium oxide,ITO, yttrium oxide, zirconium oxide, or aluminum oxide, as a maincomponent; nitride films each containing a nitride such as siliconnitride, aluminum nitride, or boron nitride as a main component; andoxynitride films each containing an oxynitride such as sialon. Ofcourse, for example, the underlayer (underlying film) may also be formedby using the foregoing oxides alone, or two or more of the oxides inmixture, or mixtures other than the oxides. The composition of theunderlayer has no particular restriction. However, Bi and/or Sb tends tobond to oxygen. Therefore, if oxygen is contained in the underlyingfilm, Bi and/or Sb is also diffused and concentrated in the interfacebetween the underlying film and the Ag alloy film, resulting in animprovement in adhesion. Therefore, out of the foregoing underlyingfilms, a film containing oxygen like oxide or oxynitride is desirablefrom the viewpoint of improving the adhesion.

These underlayers may be either of single layers or multilayers. Whenthe underlayers are formed in multilayers, the foregoing underlayers andfilms of other compositions than that of the underlayers may be used incombination to form multilayers. Out of these, use of the one havinghigh refractive index such as titanium oxide as the underlayer canprovide satisfactory visible light transmittance while suppressingoptical reflection, and hence it is desirable.

The process for forming the underlying film (underlayer) has noparticular restriction. The underlying film (underlayer) may be formedon the substrate using a process suitable for the composition of theunderlying film. Examples of such a process include a sputteringprocess, a plasma CVD-process, and a sol-gel process.

The film thickness of the underlying film has no particular restriction,but, in general, it is recommendably set at about 10 nm to 1000 nm. Ifit is less than 10 nm, the intended purpose, for example, achieving ofthe reduction in optical reflectance while ensuring the satisfactoryvisible light transmittance may be impossible. Whereas, if it exceeds1000 nm, the adhesion may be undesirably reduced due to the film stress.More preferably, it is 100 nm or less.

In order to further improve the durability and the weather resistance inaddition to the same purposes as with the underlayer, alternatively, inorder to further improve the characteristics such as chemicalresistance, abrasion resistance, damage resistance, and Ag aggregationresistance according to the usage environment, a protective film mayalso be disposed on the Ag alloy film.

The protective layer to be formed on the electromagnetic-shielding Agalloy film has no particular restriction. However, it preferably hastransparency from the viewpoint of visible light transmittance. Further,it is recommendably an amorphous film from the viewpoint of durabilitiesto oxygen and moisture. As such a protective layer, the film having thesame composition as that of the underlying film may also be used. Thefilms mentioned as examples of the underlying layers are desirable asprotective layers. Out of these, desirably, a material is appropriatelyselected from aluminum oxide, silicon nitride, aluminum nitride, boronnitride, sialon, and the like to form a protective layer from theviewpoints of abrasion resistance and damage resistance. Whereas, oxidesand oxynitrides are preferred from the viewpoints of the weatherresistance, and durabilities to an atmosphere containing a halogenelement such as salt water. This is for the following reason. When theprotective film is an oxide film or an oxynitride film containingoxygen, oxygen is present during deposition, so that Bi and/or Sb isdiffused onto the Ag alloy film, and oxidized to form an oxide. As aresult, the cut-off property with environment by the oxide layer of Biand/or Sb is improved as a matter of course. Further, the adhesion withthe protective film is improved, and the pinholes in the protective filmare reduced in number. Accordingly, the environment cut-off property isfurther improved. In particular, out of the oxides, ITO, zinc oxide, tinoxide, and indium oxide are preferred in terms of the adhesion with theconcentrated layer of Bi and/or Sb and less pinholes. These protectivelayers may be either single layers or multilayers. When the protectivelayers are formed in multilayers, the protective layers mentioned aboveas examples and films of other compositions than that of the protectivelayers may be used in combination to form multilayers.

The process for forming the protective layer has no particularrestriction. The protective layer may be formed on the Ag alloy filmusing a process suitable for the composition of the protective layer.Examples of such a process include a sputtering process, a plasma CVDprocess, and a sol-gel process.

The film thickness of the protective layer has no particularrestriction, but, in general, it is recommendably set at about 10 nm to1000 nm. If it is less than 10 nm, the abrasion resistance and thedamage resistance may not be satisfactorily obtainable, and pinholes arenot satisfactorily reduced in number. Whereas, if it exceeds 1000 nm,the adhesion may be undesirably reduced due to the film stress. Morepreferably, it is 100 nm or less.

Incidentally, the underlayer, the Ag alloy film, and the protectivelayer may also be stacked alternately on the substrate.

Examples of the substrate for forming thereon the Ag alloy film (or theunderlayer) in accordance with the present invention may include glass,plastic, and resin film. When the film is used for an application inwhich visible light transmission is required, such as a window pane, asubstrate having transparency (i.e., visible light transmittivity) isdesirably used. In this case, the substrate has no particularrestriction as to the material, composition, thickness, and the like solong as it can transmit a visible light therethrough. Whereas, when thesubstrate is not required to have transparency, namely, when the Agalloy film is used mainly for the purpose of electromagnetic shielding,for example, the Ag alloy film is mounted internally in or externally onelectronic equipments, it has no particular restriction as to the kind,composition, transparency, thickness, and material of the substrate, andthe like.

In the present invention, the substrates may be used alone or inplurality thereof, and the combination thereof has no particularrestriction. For the purpose of further improvement of thecharacteristics, various substrates and/or at least one layer ofelectromagnetic-shielding Ag alloy film, and further, if required, theunderlayer, and the protective layer may be used in combination,resulting in a multilayer. Namely, the electromagnetic-shielding Agalloy film-formed product in accordance with the present invention maybe configured such that the electromagnetic-shielding Ag alloy film inaccordance with the present invention is formed on a substrate.Alternatively, it may also be configured as follows. On the substrate, afilm containing at least one selected from the group consisting ofoxide, nitride, and oxynitride is formed as an underlayer. On theunderlayer, the electromagnetic-shielding Ag alloy film in accordancewith the present invention is formed. On the Ag alloy film, a filmcontaining at least one selected from the group consisting of oxide,nitride, and oxynitride is formed as a protective layer.

For example, when the product is used for the application in whichvisible light transmission is required, it is recommendably formed sothat the Ag alloy film or the like is on the indoor side. If the film isformed on the outdoor side, there is unpreferably a high possibilitythat flaws occur on the film due to external factors (such as pebblesand dust). Whereas, even if the film is set on the indoor side, flawsmay occur on the film due to the external factors. For this reason, ingeneral, the film on which the Ag alloy film or the like is formed isdesirably used in such a state so as not to be directly exposed toexternal environment. Therefore, the Ag alloy film-formed product inaccordance with the present invention may be a substrate single layer.However, it may also be a multilayer made of a combination of aplurality of substrates from the viewpoint of protecting the Ag alloyfilm from the external factors. The combination for the multilayer hasno particular restriction. Examples of the product in the case whereglass having transparency is used as a substrate may include insulatingglass and laminated glass. Incidentally, considering the indoor heatinsulating property, noise insulating property, and the like, requiredaccording to the living environment, the substrate is recommendablyformed into an insulating glass or a laminated glass from the viewpointof durability. The combination when the substrate is formed into aninsulating glass has no particular restriction. Desirable examples ofthe insulating glass include the one hermetically sealed so that airlayers (space layers) are disposed by using a plurality of glass plates,and disposing spacers or the like between the adjacent glass plates. Insuch a case, a dry air or a nitrogen gas is preferably filled in the airlayers from the viewpoint of preventing the corrosion between the glassplates. Whereas, formation of the Ag alloy film on the air layer side ofthe outside glass or on the air layer side of the inside glass canattain the prevention of damaging during factory manufacturing, andhence it is desirable. This is also the same for the case using atransparent member other than the case using glass having transparencyas a substrate. The product is recommendably formed in a multilayerstructure in which the transparent member is stacked on the Ag alloyfilm (or a protective layer further formed on the Ag alloy film) formedon a substrate (transparent substrate) made of the transparent member.In this case, preferably, the transparent members are stacked throughspacers, and a space layer is disposed between the transparent memberand the underlying film (Ag alloy film or protective layer).

When the electromagnetic-shielding Ag alloy film in accordance with thepresent invention is used for the application in which visible lighttransmission is not required, the Ag alloy film may be formed insideand/or outside of each cover of equipments requiring electromagneticshielding such as electronic equipments. Alternatively, the Ag alloyfilm may also be formed on any side of an electromagnetic-shieldingplate. Of course, as described above, the film may be formed in amultilayer in order to protect the Ag alloy film from the externalfactors. An underlayer, a protective layer, and the like may also beformed according to uses. Of course, a laminated film obtained bycoating the polymer film with the Ag film may be bonded on a substrateto mount the Ag film internally in or externally on equipments.

The electromagnetic-shielding Ag alloy film in accordance with thepresent invention is recommendably formed on the substrate by asputtering process. When a pure Ag film is formed on the substrate by adeposition process such as a sputtering process, an island film isformed with a thickness of up to about several tens nanometers, and thesurface energy of Ag is in a high state. Thus, if the Ag film isdirectly exposed to air, the surface energy of Ag is further raised.Therefore, it is conceivable that the aggregation of Ag becomes morelikely to occur in order to reduce the surface energy. However, for theAg alloy film to which Bi and/or Sb has been added, conceivably, thesurface energy of Ag is low, so that the surface diffusion of Ag issuppressed, which allows the suppression of aggregation. In particular,conceivably, when the Bi- and/or Sb-incorporated Ag alloy film has beenexposed to an atmosphere in which oxygen is present, Bi and/or Sb isdiffused in the surface of Ag, and bonds to oxygen, thereby to form anoxide. This cuts off the Ag alloy film from the environment, and reducesthe surface energy of Ag. Accordingly, the surface diffusion of Ag isfurther suppressed, which allows the suppression of aggregation.Conceivably, if one or more elements of Cu, Au, Pd, Rh, Ru, Ir, and Ptare added to the Ag alloy film, the surface energy is further reduced,so that the aggregation of Ag is still further suppressed. Whereas, asfor the additive elements Bi and/or Sb in accordance with the presentinvention, if oxygen is contained in the substrate, the underlying filmand the protective film, Bi and/or Sb is diffused and concentrated inthe surface of the Ag alloy film. Accordingly, the composition of Biand/or Sb inside the Ag alloy film becomes a low value. As a result, theelectrical resistivity is reduced, resulting in very excellentelectromagnetic shielding characteristics.

As the sputtering target for deposition by a sputtering process of theelectromagnetic-shielding Ag alloy film, there may be used a sputteringtarget made of an Ag base alloy which contains at least any one of Bi:0.2 to 23 at % and Sb: 0.01 to 10 at %, and has a Bi content and a Sbcontent satisfying the formula (2-1). In this case, as the sputteringtarget material, the Ag base alloy manufactured by a dissolution/castingprocess (below, also referred to as a melt-produced Ag base alloy targetmaterial) is preferably used. Such a melt-produced Ag base alloy targetmaterial is uniform in structure, and uniform in sputtering rate andoutgoing angle, so that it is possible to obtain an Ag base alloy filmuniform in composition with stability. As a result, it is possible toobtain a higher performance Ag alloy film-formed product. Incidentally,control of the oxygen content of the melt-produced Ag alloy targetmaterial (preferably at 100 ppm or less) makes it easy to keep the filmformation rate constant, and also allows the reduction in oxygen contentin the Ag base alloy film. Therefore, it is possible to enhance thecorrosion resistance of the Ag alloy film.

In this case, as a sputtering target (below, also referred to as atarget) for obtaining an electromagnetic-shielding Ag alloy filmcontaining Bi and/or Sb in a total amount of 0.01 to 10.0 at %, theremay be used the one made of the Ag base alloy which contains at leastany one of Bi: 0.2 to 23 at % and Sb: 0.01 to 10 at %, and has a Bicontent and a Sb content satisfying the formula (2-1). Incidentally,when the Ag alloy film is formed by sputtering using a target made of aBi-containing Ag base alloy, the Bi content in the Ag alloy film is lessthan the Bi content in the target, and quantitatively several percent toseveral tens percent of the Bi content in the target. For this reason,as the target for obtaining a Bi-containing Ag alloy film, a targethaving a larger Bi content than the Bi content of the Ag alloy film isrequired to be used. More specifically, as the target for obtaining anAg alloy film containing Bi: 0.01 to 10.0 at %, a target containing Bi:0.2 to 23 at % is required to be used. From such a point, the target inaccordance with the present invention is configured as a target of theforegoing composition. Namely, for Bi, when it is contained, there isadopted a target having a larger Bi content than the Bi content of theAg alloy film to be obtained.

Thus, when the Ag alloy film is formed by sputtering using a target madeof a Bi-containing Ag base alloy, the Bi content in the Ag alloy film isless than the Bi content in the target. This is conceivably caused bythe following factors: Bi has a lower melting point than that of Ag, andthe difference in melting point between Ag and Bi is large, andtherefore Bi is revaporized from the top of the substrate duringdeposition (during sputtering); and/or Bi is difficult to sputterbecause the sputtering rate of Ag is larger than the sputtering rate ofBi; and/or Bi is more susceptible to oxidation than Ag, so that only Biis oxidized on the target surface, and is not sputtered; and/or otherfactors.

Incidentally, as described above, the total amount of Bi and Sbcontained in the Ag alloy film is required to be 0.01 at % or more and10 at % or less. For this reason, the amounts of Bi and Sb contained inthe target are also required to meet the formula (2-1). This is alsocaused by the difference between the Bi content in the target and the Bicontent in the Ag alloy film.

Incidentally, the coefficient on the Bi content in the target (i.e., theformula of 0.000502x³+0.00987x²+0.0553x and the coefficient) in theformula (2-1) is obtained by approximation from the results ofexperimental examination on the correlation between the Bi content inthe target and the Bi content in the Ag alloy film.

When the electromagnetic-shielding Ag alloy film in accordance with thepresent invention is used for electromagnetic shielding, a sputteringtarget is preferably used which is made of an Ag base alloy containingat least any one of Bi: 0.2 to 12 at % and Sb: 0.01 to 5 at %, andhaving a Bi content and a Sb content satisfying the following formula(2-2):0.01 at %≦0.000502x ³+0.00987x ²+0.0553x+Sb content≦5 at %  Formula(2-2)

where, in the formula (2-2), x denotes the Bi content (at %) in thetarget, and Sb content denotes the Sb content (at %) in the target.

The conditions for the sputtering process has no particular restriction,and known sputtering processes may be employed.

As the infrared-shielding sputtering target, the one containing Ag as amain component, and at least any one of Bi: 0.2 to 12 at % and Sb: 0.05to 5 at %, and having a Bi content and a Sb content satisfying thefollowing formula (2-3) is desirable, and the one containing at leastone of Bi: 0.5 to 8 at % and Sb: 0.10 to 3 at %, and having a Bi contentand a Sb content satisfying the following formula (2-4) is moredesirable.0.05 at %≦0.000502x ³+0.00987x ²+0.0553x+Sb content≦5 at %  Formula(2-3)0.10 at %≦0.000502x ³+0.00987x ²+0.0553x+Sb content≦3 at %  Formula(2-4)

where, in the formulae (2-3) and (2-4), x denotes the Bi content (at %)in the target, and Sb content denotes the Sb content (at %) in thetarget.

As the electromagnetic-shielding sputtering target, the one containingAg as a main component, and at least any one of Bi: 0.2 to 12 at % andSb: 0.01 to 5 at %, and having a Bi content and a Sb content satisfyingthe following formula (2-5) is desirable, the one containing at leastone of Bi: 0.5 to 8 at % and Sb: 0.05 to 3 at %, and having a Bi contentand a Sb content satisfying the following formula (2-6) is morepreferred, and the one containing at least one of Bi: 0.5 to 5 at % andSb: 0.10 to 1 at %, and having a Bi content and a Sb content satisfyingthe following formula (2-7) is further preferred.0.01 at %≦0.000502x ³+0.00987x ²+0.0553x+Sb content≦5 at %  Formula(2-5)0.05 at %≦0.000502x ³+0.00987x ²+0.0553x+Sb content≦3 at %  Formula(2-6)0.10 at %≦0.000502x ³+0.00987x ²+0.0553x+Sb content≦1 at %  Formula(2-7)

where, in the formulae (2-5), (2-6), and (2-7), x denotes the Bi content(at %) in the target, and Sb content denotes the Sb content (at %) inthe target.

If these targets are allowed to contain at least one element selectedfrom Cu, Au, Pd, Rh, Ru, Ir, and Pt in a total amount of 0.3 at % ormore, it is possible to further improve the effect of suppressing theaggregation of Ag. Incidentally, the amount of these elements (Cu, Au,Pd, Rh, Ru, Ir, and Pt) to be added is more preferably 0.5 at % or more,and further preferably 0.8 at % or more. On the other hand, the upperlimit of the amount of these elements (Cu, Au, Pd, Rh, Ru, Ir, and Pt)to be added has no particular restriction. However, the upper limit ispreferably 10 at %, more preferably 8 at %, and further preferably 5 at%.

The electromagnetic-shielding Ag alloy film deposited by a sputteringprocess using the sputtering target obtained by adding the additiveelements (Bi and/or Sb, or further one or more of Cu, Au, Pd, Rh, Ru,Ir, and Pt) to Ag is excellent in electromagnetic shieldingcharacteristics (infrared shielding property and radio wave shieldingproperty), and excellent in visible light transmittivity, durability,weather resistance, and Ag aggregation resistance.

The electromagnetic-shielding Ag alloy film in accordance with thepresent invention is recommendably deposited by a sputtering process asdescribed above. However, it may also be deposited by a physical vapordeposition process such as a vacuum deposition process or a chemicalvapor deposition process such as a CVD process.

In the present invention, as described above, the Ag alloy film has alayer (below, also referred to as a Bi-/Sb-rich layer) having a largerBi and/or Sb content than the inside of the Ag alloy film at the surfaceand/or interface of the Ag alloy film. The Bi-/Sb-rich layer is presentat the surface and/or interface of the Ag alloy film. The Bi-/Sb-richlayer is present only at the surface of the Ag alloy film, or is presentonly at the interface of the Ag alloy film. Alternatively, it is presentboth at the surface and the interface of the Ag alloy film.

In this case, the surface of the Ag alloy film denotes the region otherthan the inside of the Ag alloy film, and it is not limited to only theoutermost surface, or to only the outermost surface and the vicinitythereof. The region (layer) from the outermost surface to the site at athickness (depth) of about ¼ of the Ag alloy film thickness is alsoincluded in the surface of the Ag alloy film. In such a region (layer),the Bi-/Sb-rich layer is present (in the case where the Bi-/Sb-richlayer is present in the surface of the Ag alloy film). Whereas, theinterface of the Ag alloy film is, when other films or layers aredisposed (stacked) on the surface of the Ag alloy film, the interfacebetween the other films or layers and the Ag alloy film. As for theinterface of the Ag alloy film, it has the same meaning as with thesurface of the Ag alloy film, and it is not limited to only theinterface, or only the interface and the vicinity thereof. The region(layer) from the interface to the site at a thickness (depth) of about ¼of the Ag alloy film thickness is also included in the interface of theAg alloy film. In such a region (layer) the Bi-/Sb-rich layer is present(in the case where the Bi-/Sb-rich layer is present in the interface ofthe Ag alloy film). Incidentally, the inside of the Ag alloy filmdenotes the region (layer) between the side at a thickness (depth) ofabout ¼ and the site at a thickness (depth) of about ¾ of that of the Agalloy film from the surface or the interface of the Ag alloy film.

In the present invention, the foregoing Bi-/Sb-rich layer containsoxidized Bi and/or oxidized Sb. The Bi-/Sb-rich layer often comprisesoxidized Bi and/or oxidized Sb. However, it is not limited thereto. Italso covers the case where it contains oxidized Bi and/or oxidized Sb asa main component, and the case where Bi and/or Sb is also present otherthan oxidized Bi and/or oxidized Sb.

Then, an embodiment of a third invention will be described.

The present inventors have carried out an environmental test in which anoptical reflective film (film thickness 100 nm) of Ag alone is allowedto stand for 48 hours under high temperatures and high humidities of atemperature of 80° C. and relative humidity of 90% in order toacceleratingly ascertain the phenomenon occurring when the opticalreflective film has been exposed in air during manufacturing of a liquidcrystal display device or when it has been exposed under hightemperatures and high humidities for a long time during use aftermanufacturing. It has been shown that the reflectance of the opticalreflective film is decreased by about 7.0% after the environmental testas compared with the reflectance (wavelength 650 nm) before theenvironmental test. The reduction in reflectance (below, referred to as“reduction with time in reflectance”) is conceivably due to the factorssuch as the growth of crystal grains and the aggregation of Ag atoms asdescribed in the foregoing description of the related art.

Under such circumstances, the present inventors have conducted a closestudy based on the idea that, in order to prevent the reduction withtime in reflectance, and obtain high reflectance inherent in Ag, findingof an alloy component capable of removing or inhibiting the factors isimportant.

As a result of the study, the present inventors have found as follows.By allowing Ag to contain Bi and/or Sb (one or two elements selectedfrom the group consisting of Bi and Sb), it is possible to suppress theaggregation of Ag and crystal grain growth while keeping the highreflectance inherent in Ag, and to inhibit the reduction with time inreflectance. This has led to the completion of the present invention.

Conventionally, a study has been made to use not only pure Ag but alsoan Ag base alloy as an optical reflective film. However, the findingthat the aggregation of Ag atoms and the growth of crystal grains of Agare suppressed by adding Bi and Sb to Ag as defined in the presentinvention is not observable in the related art. As for the suppressionof the aggregation of Ag atoms and the crystal grain growth of Ag, thereis the invention of an optical reflective film comprising an Ag basealloy to which rare earth elements have been added (JP-B No. 01729/2002)by the present inventors. However, the optical reflective filmcomprising a Bi- and Sb-containing Ag base alloy in the presentinvention has higher reflectance and durability.

In the present invention, by using an Ag base alloy containing Bi and/orSb as an optical reflective film, the reduction with time in reflectanceis suppressed, so that high optical reflectance is kept. Therefore, thepresent invention is based on the technical idea distinctlydistinguishable from the related art. Incidentally, as described later,an alloy obtained by adding low-cost rare earth elements such as Nd andY to an Ag base alloy containing Bi and/or Sb is also usable. Further,ternary, or quaternary or more alloys containing Au, Cu, Pt, Pd, and Rhwhich are the components for improving the oxidation resistance are alsousable. Below, the present invention will be described in details.

In the present invention, in view of the point that the opticalreflective film for use in, for example, a reflective type liquidcrystal display device or the like is required to have reflectioncharacteristics of a visible light, the reflectance was measured at awavelength of 650 nm to study the reflection characteristics.Incidentally, in the following description, “initial reflectance (%)”denotes the reflectance (%) immediately after formation of the opticalreflective film. The magnitude of the value is dependent upon the kindand the amount of the alloy element. Whereas, “the amount of change withtime of reflectance (%)” is defined as “reflectance after environmentaltest (%)−initial reflectance (%)”. When the amount of change with time(%) is minus, it is meant that the reflectance after environmental testis reduced than the initial reflectance.

If the optical reflective film is formed of an Ag base alloy containingBi and/or Sb, the growth of crystal grains of Ag and the aggregation ofAg atoms are suppressed. In particular, the thin film formed by asputtering process contains a large-number of defects such as atomvoids. Accordingly, Ag atoms tend to move/are diffused. Conceivably,this results in aggregation of Ag atoms. The presence of Bi and Sb inthe crystal of Ag suppresses the movement/diffusion of Ag atoms.Conceivably, this results in suppression of crystal grain growth of Agand the aggregation of Ag atoms.

By adding Bi and/or Sb in a total amount of 0.01 at % or more, theeffects of suppressing the growth of crystal grains of Ag and theaggregation of Ag atoms are produced. However, the reduction in initialreflectance or the increase in electrical resistivity is entailed withan increase in amount of these elements to be added. Therefore, thetotal amount of Bi and/or Sb to be added is preferably set at 4 at % orless. In particular, when a liquid crystal display device serves as botha reflector and an electrode, the electrical resistivity is desirablyset as low as possible. Namely, as for the initial reflectance, if thetotal amount of Bi and/or Sb to be added is set within 2 at %, it ispossible to keep a high initial reflectance of 80% or more. On the otherhand, as for the electrical resistivity, in general, the electricalresistivity of an Al alloy (such as Al—Ta or Al—Nd) to be used as awiring film of the liquid crystal display device is about 5 to 15 μΩcm.For this reason, if the amount of both Bi and Sb is set within 1.8 at %as shown in examples described later, it is possible to obtain anelectrical resistivity of not more than 15 μΩcm equal to that of an Alalloy wiring. However, for a refractory metal of high melting point suchas Cr or Mo to be used for the liquid crystal display device wiring filmas with the Al alloy, it is used with an electrical resistivity up toabout 200 μΩcm. Accordingly, even when the amount of Bi and Sb to beadded exceeds 1.8 at %, the film is usable without a problem. Therefore,the more preferred upper limit of the total amount of Bi and/or Sb is 2at %.

On the other hand, as an environmental test for acceleratinglyreproducing the environment in which the crystal grain growth of Ag andthe aggregation of Ag atoms tend to occur, the optical reflective filmwas allowed to stand for 48 hours under a high-temperature high-humidityenvironment of a temperature of 80° C. and a relative humidity of 90%.Even in this case, if Bi and/or Sb is present in a total amount of 0.05at % or more, it is possible to control the difference between thereflectance before the environmental test [=initial reflectance] (%) andthe reflectance (%) after the environmental test to 1% or less.Accordingly, the mote preferred lower limit of the total amount of Biand/or Sb is 0.05 at %.

In the Ag base alloy to be used for the formation of the opticalreflective film of the present invention, further, rare earth elements,particularly Nd and/or Y may also be contained. This is due to thefollowing facts. Nd and Y also have an effect of improving theaggregation resistance of Ag although they produce a smaller effect ascompared with Bi and Sb described above. In addition, Nd and Y require alower material cost as compared with Bi and Sb. Therefore, replacementof a part of Bi and Sb therewith allows the cost reduction.Incidentally, the total amount of Nd and/or Y to be added is preferablyset at 0.01 at % or more. However, the addition of Nd and Y entails thereductions in initial reflectance and electrical resistivity. Therefore,the total amount thereof is set at preferably 2 at % or less, and morepreferably 1 at % or less. (Incidentally, even if only Nd and/or Y isadded to Ag without adding Bi and/or Sb thereto, it is possible toimprove the aggregation resistance of Ag, but a problem is encounteredthat the NaCl resistance is not improved as described in the followingexamples).

Au, Cu, Pt, Pd, Rh, and the like may also be added for the purpose ofimproving the oxidation resistance. These elements do not have an effectof suppressing the aggregation of Ag, but they have an effect ofincreasing the chemical stability, and have a function of inhibiting thereduction with time in reflectance. Incidentally, these elements entailsa reduction in reflectance particularly in a short wavelength region(around 400 nm) with an increase in amount added. For this reason, thetotal amount is set at preferably 3 at % or less, and more preferably 2at % or less.

An preferred embodiment for obtaining a high initial reflectance is suchthat the optical reflective film of the present invention contains Biand/or Sb, and if required, contains Nd and Y, or Cu, Au, Pd, Rh, andPt, with the balance being substantially Ag. However, other componentsthan the foregoing components may also be added so long as they areadded in such a range as not to impair the function of the presentinvention. For example, Zn, Ti, Mg, Ni, and the like may also be addedfrom the viewpoints of chemical corrosion and reaction prevention.Whereas, gas components such as Ar, O₂, and N₂, and impurities containedin the Ag base alloy which is a molten raw material are also allowable.

The optical reflective film of the present invention can keep highreflectance for a long time, and hence it is preferably used for areflection type liquid crystal display device. Further, the opticalreflective film of the present invention is excellent in resistance tothe structural changes such as the crystal grain growth during heating.Therefore, it is particularly suitable for a liquid crystal displaydevice which goes through a heating step of generally 200 to 300° C.during manufacturing steps. Further, the optical reflective film has aconductivity, and hence it is available as a reflection electrode of areflection type liquid crystal display device. Alternatively, it mayalso be disposed as a reflector on the back of a transparent electrode.As the electrode substrates when the optical reflective film is used asa reflection electrode, known ones such as a glass substrate and aplastic film substrate are available. The same ones are also availablefor the base materials of the reflectors. Further, the opticalreflective film can be used in such a manner as to also serve as awiring film.

A sputtering process is preferably used for forming the opticalreflective film on the substrate or the base material. Bi and Sb have avery low solubility limit with respect to Ag in a chemical equilibriumstate. However, for the thin film formed by a sputtering process,non-equilibrium solid solution becomes possible by vapor phase quenchinginherent in a sputtering process. Therefore, as compared with the casewhere an Ag base alloy thin film is formed by other thin film formationprocess, the foregoing alloy elements tend to be uniformly present inthe Ag matrix. As a result, the oxidation resistance of the Ag basealloy is improved, and the suppression effect against the aggregation ofAg atoms is exerted.

The film thickness of the optical reflective film is preferably 50 to300 nm. For a thin film with a thickness of less than 50 nm, lightstarts to transmit therethrough, and hence the reflectance is reduced.On the other hand, when the thickness exceeds 300 nm, there is noproblem for reflectance, but disadvantages occur in terms ofproductivity and cost.

For sputtering, as a sputtering target (below, also simply referred toas a “target”), the Ag base alloy which contains one or two elementsselected from the group consisting of Bi: 0.2 to 15 at % and Sb: 0.01 to4 at %, and has a Bi content and a Sb content in the sputtering targetsatisfying the following reshown formula (3-1) is used. As a result, itis possible to obtain an optical reflective film of a desirable chemicalcomposition.0.01≦0.000502nBi³+0.00987nBi²+0.0553nBi+nSb≦4  (3-1)Where, in the formula (3-1), nBi denotes the Bi content (at %) in the Agalloy sputtering target, and nSb denotes the Sb content (at %) in the Agalloy sputtering target; and at % denotes atom %.

Herein, the reason for setting the content of Bi in the opticalreflective film higher than the content of Bi in the target is asfollows. Namely, when an optical reflective film is formed by asputtering process using a target made of a Bi-containing Ag base alloy,it is observed that the Bi content in the optical reflective film isreduced to several percent to several tens percent of the Bi content inthe target. This is conceivably caused by the following factors: Bi isrevaporized from the top of the substrate during deposition because of alarge difference in melting point between Ag and Bi; Bi is difficult tosputter because the sputtering rate of Ag is higher than the sputteringrate of Bi; only Bi is oxidized on the target surface because Bi is moresusceptible to oxidation than Ag, and is not sputtered; and otherfactors. The phenomenon that the element content in the opticalreflective film is largely reduced from the element content in thetarget in this manner is the phenomenon not observable for other Ag basealloys such as Ag—Sb alloy and Ag-rare earth metal alloy. For thisreason, the Bi content in the target is required to be set higher thanthe Bi content in the objective optical reflective film. For example, inorder to obtain an optical reflective film containing Bi in an amount of0.005 to 0.4 at %, the Bi content in the target is required to be set at0.15 to 4.5 at % in consideration of the content of Bi which will not beincorporated into the optical reflective film (see Example 4 describedlater). Incidentally, as described previously, the total amount of Biand Sb contained in the optical reflective film is required to be set at0.01 to 4 at %. For this reason, the Bi content and the Sb content inthe target is required to satisfy the foregoing numerical value range,and satisfy the formula (3-1).

Herein, the value of each coefficient on nBi in the formula (3-1) isobtained by approximation from the results of experimental examinationon the correlation between the Bi content in the target and the Bicontent in the optical reflective film.

As a target, the Ag base alloy (melt-produced Ag base alloy)manufactured by a dissolution/casting process is preferably used. Themelt-produced Ag base alloy is uniform in structure, and the sputteringrate and the outgoing angle can be set constant, so that it is possibleto obtain an optical reflective film uniform in composition. If theoxygen content of the melt-produced Ag base alloy target is controlledat 100 ppm or less, it becomes easy to keep the film formation rateconstant, and the oxygen content in the optical reflective film alsobecomes lower. Therefore, the reflectance and the electrical resistivityare improved.

The reflection type liquid crystal display device of the presentinvention may properly include the optical reflective film of thepresent invention, and has no other particular restriction as to theconstitution as a liquid crystal display device. All known constitutionsin the field of a liquid crystal display device are adoptable.

Below, the present invention will be described in more details by way ofexamples. However, the following examples should not be construed aslimiting the scope of the invention. All of modifications or changespracticed within a scope not departing from the spirit of the presentinvention are included in the technical range of the present invention.

Example 1

First, the measurement and evaluation method of each characteristic willbe described below.

[Manufacturing of Ag Base Alloy Thin Film]

Using composite targets each formed by locating chips of variousadditive elements on a pure Ag sputtering target, each thin film of pureAg (sample No. 1), Ag—Bi alloys (sample Nos. 2 to 5), Ag—Sb alloys(sample Nos. 6-9), Ag—Bi—Nd alloys (sample Nos. 10 to 14), Ag—Bi—Yalloys (sample Nos. 15-19), Ag—Sb—Nd alloys (sample Nos. 20 to 24),Ag—Sb—Y alloys (sample Nos. 25 to 29), Ag—Bi—Cu alloys (sample Nos. 30to 34), Ag—Bi—Au alloys (sample Nos. 35 to 39), Ag—Sb—Cu alloys (sampleNos. 40 to 44), Ag—Sb—Au alloys (sample Nos. 45 to 49), Ag—Bi—Nd—Cualloy (sample No. 50), Ag—Bi—Nd—Au alloy (sample No. 51), Ag—Bi—Y—Cualloy (sample No. 52), Ag—Bi—Y—Au alloy (sample No. 53), Ag—Sb—Nd—Cualloy (sample No. 54), Ag—Sb—Nd—Au alloy (sample No. 55), Ag—Sb—Y—Cualloy (sample No. 56), Ag—Sb—Y—Au alloy (sample No. 57), Ag—Si alloy(sample No. 58), and Ag—Sn alloy (sample No. 59), with a film thicknessof 100 nm (as a reflective film), or 15 nm (as a semi-transmissivereflective film) was deposited on a polycarbonate substrate (diameter:50 mm, thickness: 1 mm) with a DC magnetron sputtering process. Then,each composition of these Ag base alloy thin films were examined by anICP (inductively coupled plasma) mass spectroscopy.

Then, using each Ag base alloy thin film manufactured, thecharacteristics (thermal conductivity, reflectance, and durability) as areflective film (film thickness 100 nm) or a semi-transmissivereflective film (15 nm) were examined. In particular, as for the thermalstability out of the durabilities, the changes in reflectance before andafter a high-temperature high-humidity test, surface roughness (averageroughness), crystal grain diameter, and the like were examined. As forthe chemical stability out of the durabilities, the changes inappearance after a salt immersion test were examined. Thus, thedurabilities of each thin film were evaluated.

Example 1-1 Measurement of Thermal Conductivity

The thermal conductivity of each thin film with a thickness of 100 nmmanufactured as described above was measured in the following manner.The sheet resistance Rs was measured with a four probe method by meansof 3226-μΩ Hi TESTER manufactured by HIOKI Co, and the film thickness twas measured by means of alpha-step 250 manufactured by TENCORINSTRUMENTS Co. Then, the electrical resistivity ρ (=sheet resistanceRs×film thickness t) was calculated, and then, the thermal conductivityκ (=2.51×absolute temperature T/electrical resistivity ρ) at an absolutetemperature of 300 K (≈27° C.) was calculated by the law ofWiedemann-Franz. Incidentally, for the evaluation, the one showing 256W/(m·K) or more, which corresponds to 80 percent or more of the thermalconductivity: 320 W/(m·K) of a pure Ag thin film has been judged ashaving high thermal conductivity. The results are shown in Tables 1 and2.

As apparent from Tables 1 and 2, any of the pure Ag thin film (sampleNo. 1), the Ag—Si alloy (sample No. 58) thin film, and the Ag base alloythin films of sample Nos. 2 to 4, 6 to 8, 10 to 13, 15 to 18, 20 to 23,25 to 28, 30 to 33, 35 to 38, 40 to 43, 45 to 48, and 50 to 57, whichsatisfy the defined requirements of the present invention has highthermal conductivity. In contrast, for the Ag base alloy thin films ofsample Nos. 5, 9, 14, 19, 24, 29, 34, 39, 44, and 49, it is not possibleto obtain a prescribed high thermal conductivity because of the toolarge amount of the alloy elements to be added. Whereas, also for thethin film of the Ag—Sn alloy (sample No. 59), it is not possible toobtain high thermal conductivity. Incidentally, the addition effects ofRh, Pd, and Pt are the same as the addition effects of Cu or Au.

[see Tables 1, 2]

Example 1-2 Measurement of Reflectance

The reflectance with respect to a visible light (wavelength: 400 to 800nm) of each thin film with a thickness of 100 nm manufactured in theforegoing manner was measured by means of Polar Kerr Scope NEO ARK MODELBH-810 manufactured by Nihon Kagaku Engineering Co. Incidentally, forthe evaluation of high reflectance, the one showing 80% or more(wavelength 405 nm) and 88% or more (wavelength 650 nm) relative to90.8% (wavelength 405 nm) and 92.5% (wavelength 650 nm), respectively,which are the reflectances of the pure Ag thin film has been judged ashaving a high reflectance. Herein, the wavelength of 405 nm is thewavelength of a laser light to be used for a next-generation opticaldisk, and the wavelength of 650 nm is the wavelength of a laser light tobe used for a DVD. The results are shown in Tables 3 and 4.

As apparent from Tables 3 and 4, any of the pure Ag thin film (sampleNo. 1), the thin films of the Ag—Si alloy (sample No. 58) and the Ag—Snalloy (sample No. 59), and the Ag base alloy thin films of sample Nos. 2to 4, 6 to 8, 10 to 13, 15 to 18, 20 to 23, 25 to 28, 30 to 33, 35 to38, 40 to 43, 45 to 48, and 50 to 57, which satisfy the definedrequirements of the present invention has high thermal conductivity. Incontrast, for the Ag base alloy thin films of sample Nos. 5, 9, 14, 19,24, 29, 34, 39, 44, and 49, it is not possible to obtain a prescribedhigh reflectance because of the too large amount of the alloy elementsto be added. Incidentally, the addition effects of Rh, Pd, and Pt arethe same as the addition effects of Cu or Au.

[see Tables 3, 4]

Example 1-3 Durability Test 1: Evaluation of Thermal Stability

Each of the same 100 nm-thick thin films as those used for themeasurement of the reflectance of Example 2 was subjected to ahigh-temperature high-humidity test (temperature 80° C.-humidity 90%RH-retention time 48 hours). After the test, the reflectance wasmeasured again. For the evaluation, the one showing absolute values ofthe changes in reflectance before and after the high-temperaturehigh-humidity test of 5% or less (wavelength 405 nm) and 1% or less(wavelength 650 nm) has been judged as having high durability. Theresults are shown in Tables 5 and 6.

As apparent from Tables 5 and 6, any of the Ag base alloy thin films ofthe sample Nos. 2 to 57 satisfying the defined requirements of thepresent invention has high durability. In contrast, for the thin filmsof the pure Ag (sample No. 1), the Ag—Si alloy (sample No. 58), and theAg—Sn alloy (sample No. 59), it is not possible to obtain a prescribedhigh durability. Incidentally, the addition effects of Rh, Pd, and Ptare the same as the addition effects of Cu or Au.

[see Tables 5, 6]

Example 1-4 Durability Test 2:Evaluation of Chemical Stability

Each of the 15 nm-thick thin films manufactured in the foregoing mannerwas subjected to a salt immersion test (salt water concentration: 0.05mol/l for NaCl, salt water temperature: 20° C., immersion time: 5minutes). The changes in appearance of the thin film after the test werevisually observed. For the evaluation, the one of which the changes inappearance such as discoloration and peeling were not observed have beenjudged as having high durability. The results are shown in Tables 7 and8.

As apparent from Tables 7 and 8, any of the Ag base alloy thin films ofthe sample Nos. 2 to 57 satisfying the defined requirements of thepresent invention has high durability. In contrast, for the thin filmsof the pure Ag (sample No. 1), the Ag—Si alloy (sample No. 58), and theAg—Sn alloy (sample No. 59), it is not possible to obtain a prescribedhigh durability. Incidentally, the addition effects of Rh, Pd, and Ptare the same as the addition effects of Cu or Au.

[see Tables 7, 8]

Example 1-5 Durability Test 3:Evaluation of Thermal Stability

For each of the 100 nm-thick thin films manufactured in the foregoingmanner, the surface morphology observation and the surface roughness(average roughness: Ra) measurement were carried out by means ofNanoscope IIIa scanning probe microscope manufactured by DigitalInstruments Co., in AFM: atomic force microscope mode. Then, ahigh-temperature high-humidity test (temperature 80° C.-humidity 90%RH-retention time 48 hours) was performed on each thin film subjected tothe AFM mode measurement. After the test, the surface morphologyobservation and the surface roughness (average roughness: Ra)measurement were carried out again. For the evaluation, the one whichshowed a surface roughness of less than 1 nm both before and after thehigh-temperature high-humidity test have been judged as having highdurability. The results are shown Tables 9 and 10.

As apparent from Tables 9 and 10, any of the Ag base alloy thin films ofthe sample Nos. 2 to 57 satisfying the defined requirements of thepresent invention has high durability. In contrast, for the thin filmsof the pure Ag (sample No. 1), the Ag—Si alloy (sample No. 58), and theAg—Sn alloy (sample No. 59), it is not possible to obtain a prescribedhigh durability. Incidentally, the addition effects of Rh, Pd, and Ptare the same as the addition effects of Cu or Au.

[see Tables 9, 10]

As apparent from the results of Tables 1 to 10 shown above, the Ag basealloy thin films of the samples 2 to 4, 6 to 8, 10 to 13, 15 to 18, 20to 23, 25 to 28, 30 to 33, 35 to 38, 40 to 43, 45 to 48, and 50 to 57,which satisfy the defined requirements of the present invention, havehigh performances in terms of all of high thermal conductivity, highreflectance, and high durability. In particular, the ones (sample Nos.10 to 14) obtained by adding Nd as a rare earth metal element to theAg—Bi alloy (sample No. 3), the ones (sample Nos. 15 to 19) obtained byadding Y thereto, or the ones (sample Nos. 30 to 34) obtained by addingCu thereto, and the ones (sample Nos. 35 to 39) obtained by adding Authereto have an improved durability as compared with the Ag—Bi alloy(sample No. 3). Similarly, the ones (sample Nos. 20 to 24) obtained byadding Nd as a rare earth metal element to the Ag—Sb alloy (sample No.7), the ones (sample Nos. 25 to 29) obtained by adding Y thereto, or theones (sample. Nos. 40 to 44) obtained by adding Cu thereto, and the ones(sample Nos. 45 to 49) obtained by adding Au thereto have an improveddurability as compared with the Ag—Sb alloy (sample No. 7). Further, theone (sample No. 50) obtained by adding Nd and Cu to the Ag—Bi alloy(sample No. 3), the one (sample No. 51) obtained by adding Nd and Authereto, the one (sample No. 52) obtained by adding Y and Cu thereto,and the one (sample No. 53) obtained by adding Y and Au thereto have astill further improved durability as compared with the Ag—Bi alloy(sample No. 3). Similarly, the one (sample No. 54) obtained by adding Ndand Cu to the Ag—Sb alloy (sample No. 7), the one (sample No. 55)obtained by adding Nd and Au thereto, the one (sample No. 56) obtainedby adding Y and Cu thereto, and the one (sample No. 57) obtained byadding Y and Au thereto have a still further improved durability ascompared with the Ag—Sb alloy (sample No. 7).

Example 2 Example 2-1

Using a sputtering target containing Ti as a main component, a titaniumoxide film (film thickness: 30 nm) was deposited as an underlayer on atransparent substrate (colorless float glass, board thickness: 3 mm,size: 2 cm×4 cm) by a sputtering process (under an atmosphere of a mixedgas of Ar and oxygen). The resulting plate was used as a substrate foreach test.

With a sputtering process (under an Ar gas atmosphere) using thesubstrate, an Ag alloy film (electromagnetic-shielding Ag alloy film) ofeach composition shown in Table 12 was deposited on the underlayer(titanium oxide film) of the substrate while controlling the filmthickness to be about 10 nm. At this step, as the sputtering target, thecomposite target formed by locating 5×5 mm plate-like chips (comprisingalloy components such as Bi) on a pure Ag target was used.

After the deposition of the Ag alloy film (and the pure Ag film), usinga sputtering target containing Ti as a main component, again, a titaniumoxide (film thickness: 20 nm) was deposited as a protective layer on theAg alloy film by a sputtering process (under an atmosphere of a mixedgas of Ar and oxygen). This resulted in electromagnetic-shielding Agalloy film-formed products in each of which a film of a three-layeredstructure of titanium oxide/Ag alloy film/titanium oxide had been formedon the transparent substrate.

On the other hand, in order to examine the composition of each Ag alloyfilm, only an Ag alloy film was formed on a float glass with asputtering process under the same conditions as those for the depositionof the foregoing Ag alloy film using the composite target for thedeposition of the Ag alloy film. Then, the composition of each film wasdetermined by an ICP process.

Whereas, for each electromagnetic-shielding Ag alloy film-formed productobtained by the deposition, the sheet resistance value (electricalresistance value) and the visible light transmittance were measured.Further, a high-temperature high-humidity test [allowed to stand for 48hours under an atmosphere at 85° C. and 95% Rh (relative humidity)] wascarried out. Then, the occurrence or non-occurrence of aggregation of Agwas examined, and the sheet resistance value was also measured. At thisstep, the sheet resistance value was determined by a four probe method.The aggregation of Ag was examined by the naked eye and by means of anoptical microscope observation (magnification: 200 times). The visibletransmittance was measured based on the method defined in JIS R3106.

Further, for the Ag alloy film-formed products, a salt immersion test(NaCl concentration: 0.05 mol/liter, immersion time: 15 minutes) wascarried out. The states of discoloration/peeling were visually observed.

The results of the test and the like are shown together with thecompositions of the Ag alloy films in Table 10.

Comparative Example 2-1

Ag alloy film-formed products in each of which a film of a three-layeredstructure of titanium oxide/Ag alloy film/titanium oxide had been formedon a transparent substrate were obtained in the same manner and underthe same conditions as with Example 2-1. Incidentally, the compositionsof the Ag alloy films are different from those of Example 2-1, and asshown in Table 2. Namely, the alloy component is any one of Nd, In, Nb,Sn, Cu, Al and Zn. Further, the deposition of a pure Ag film was alsocarried out using only a pure Ag target to also manufacture a pure Agfilm-formed product in which a film of a three-layered structure oftitanium oxide/pure Ag film/titanium oxide had been formed on atransparent substrate (Table 11).

For the Ag alloy film-formed products and the pure Ag film-formedproduct, the same tests were carried out in the same manner as withExamples. Further, in the same manner as with Examples, only an Ag alloyfilm was formed on each float glass to determine the composition of eachfilm with an ICP method.

The results of the tests and the like are shown together with thecompositions of the Ag alloy films in Tables 12 and 11.

Results of Example 2-1 and Comparative Example 2-1

The electromagnetic-shielding Ag alloy film-formed products inaccordance with the test Nos. 17 (Ag—In), 18 (Ag—Nb), 20 (Ag—Cu), 21(Ag—Al), and 22 (Ag—Zn) are in accordance with Comparative Example 2-1.Whereas, the one in accordance with the test No. 1 is the pure Agfilm-formed product (Ag film composition: pure Ag), and is in accordancewith Comparative Example 2-1. In these Ag alloy film-formed products andthe pure Ag film-formed product, a large number of white points wereobservable by the naked eye on the transparent substrate (glass) surfaceafter the high-temperature high-humidity test. The aggregation of Ag wasobserved (indicated with x in Tables 12 and 11).

In contrast, in the electromagnetic-shielding Ag alloy film-formedproducts of the test Nos. 2 to 16 in accordance with Example 2-1 of thepresent invention, no white point was observed by the naked eye afterthe high-temperature high-humidity test. Further, the products wereobserved by an optical microscope with a magnification of 200 times. Asa result, in the Ag alloy film-formed products in accordance with thetest No. 2, No. 3, and No. 9, in each of which the Bi and/or Sb contentin the Ag alloy film was less than 0.04 at %, out of the foregoing Agalloy film-formed products, 15 to 25 white points were observed(indicated with Δ in Table 11). However, in the Ag alloy film-formedproducts in each of which the other alloy element (additive element)content in the layer: 0.05 at % or more, ten or less white points wereobserved (indicated with ◯ in Table 11).

On the other hand, there have been shown the tendencies that the sheetresistance (electrical resistance) increases, and simultaneously thevisible light transmittance decreases with an increase in the amount ofBi and Sb to added. In general, the electromagnetic-shielding Ag alloyfilm-formed product glass preferably has a visible light transmittanceof roughly 50% or more from the viewpoint of ensuring the visibility andviewability. Further, in general, for ensuring the infrared-shieldingproperty, a sheet resistance value of roughly 40Ω/□ suffices. However,the sheet resistance value upper limit for ensuring the electromagneticshielding property is roughly 30Ω/□. (The sheet resistance value isobtained by dividing the resistivity (Ω·m) by the film thickness, andhence the physical unit is expressed as Ω. Herein, /□ is appended afterΩ, meaning that it represents the film resistance. Also hereinafter, thefilm resistance is expressed as Ω/□.)

Therefore, Table 11 indicates as follows. The amount of Bi and Sb to beadded may properly be 10 at % or less from the viewpoint of ensuring theinfrared shielding property. Whereas, the amount of Bi and Sb to beadded may properly be roughly 5 at % or less from the viewpoint ofensuring the electromagnetic shielding property.

Further, the sheet resistance value of each Ag alloy film-formed productwas measured after the high-temperature high-humidity test. As a result,for the Ag alloy film-formed product of the test No. 1 in accordancewith Comparative Example 2-1, the sheet resistance value largelyincreased by the high-temperature high-humidity test. Whereas, for theAg alloy film-formed products of the test Nos. 2 to 15 in accordancewith Example 1 of the present invention, the sheet resistance valuesless increased, and all were roughly 40Ω/□ or less.

Further, in the salt immersion test, the Ag alloy film-formed product(Ag alloy film composition: Ag—Nd) of the test No. 16 in accordance withComparative Example 2-1, judged as favorable (indicated with ◯ in Table12) in the high-temperature high-humidity test underwent discoloration(indicated with x in Table 12), and peeling. In contrast, for the Agalloy film-formed products (Ag alloy film composition: containing Bi orSb) of the test Nos. 2 to 15 in accordance with Example 2-1 of thepresent invention, less discoloration occurred (indicated with Δ and ◯in Table 11). Out of these, particularly for Bi or Sb: 0.05 at % ormore, no discoloration was observed at all (indicated with ◯ in Table11). Whereas, all the Ag alloy film-formed product in accordance withExample 2-1 of the present invention underwent no peeling.

Example 2-2

Using a target containing Al (aluminum) as a main component, an aluminumoxide film (film thickness: 20 nm) was deposited as an underlayer on atransparent substrate (colorless float glass, board thickness: 3 mm,size: 2 cm×4 cm) by a sputtering process (under an atmosphere of a mixedgas of Ar and oxygen). The resulting plate was used as a substrate foreach test.

With a sputtering process (under an Ar gas atmosphere) using thesubstrate, an Ag alloy film (electromagnetic-shielding Ag alloy film) ofeach composition shown in Table 13 was deposited on the underlayer(aluminum oxide film) of the substrate while controlling the filmthickness to be about 15 nm. At this step, as the sputtering target, thecomposite target formed by locating 5×5 mm plate-like chips (comprisingBi, Au, Cu, or Pd) on a melt-produced target of the composition of pureAg, Ag-0.2 at % Sb, or Ag-1.0 at % Sb (produced by vacuum dissolutionprocess) was used.

After the deposition of the Ag alloy film (and the pure Ag film), by asputtering process (under an atmosphere of a mixed gas of Ar and oxygen)using a sputtering target containing Al as a main component, again, analuminum oxide film (film thickness: 40 nm) was deposited as aprotective layer on the Ag alloy film. This resulted inelectromagnetic-shielding Ag alloy-formed products in each of which afilm of a three-layered structure of aluminum oxide/Ag alloyfilm/aluminum oxide had been formed on the transparent substrate.

On the other hand, in order to examine the composition of each Ag alloyfilm, only an Ag alloy film was formed on a float glass with asputtering process under the same conditions as those for the depositionof the foregoing Ag alloy film using the composite target for thedeposition of the Ag alloy film. Then, the composition of each film wasdetermined by an ICP process.

Whereas, for each electromagnetic-shielding Ag alloy film-formed productobtained by the deposition, the sheet resistance value (electricalresistance value) and the visible light transmittance were measured.Further, a high-temperature high-humidity test [allowed to stand for 240hours under an atmosphere at 85° C. and 95% Rh] was carried out. Then,the glass surface was magnified to 10 times through a projector to countthe number of aggregation points (white points) of Ag. Whereas, thesheet resistance value was also measured. At this step, the sheetresistance value was determined by a four probe method. The visibletransmittance was measured based on the method defined in JIS R3106.

The results of the test and the like are shown together with thecompositions of the Ag alloy films in Table 13.

Comparative Example 2-2

The same pure Ag film-formed product as with the test No. 1 inaccordance with Comparative Example 2-1 was manufactured. For this, thesame test as for Example 2-2 was carried out. The results are shown inTable 13.

Results of Example 2-2 and Comparative Example 2-2

The one for the test No. 23 is the pure Ag film-formed product (Ag filmcomposition: pure Ag), and is in accordance with Comparative Example2-2. In the pure Ag film-formed product, the occurrence of a largenumber of white points (aggregation points of Ag) was observable by thenaked eye after the high-temperature high-humidity test. Further, thesheet resistance value was largely increased by the high-temperaturehigh-humidity test.

In contrast, for the electromagnetic-shielding Ag alloy film-formedproduct (Ag alloy film composition: Ag-0.19 at %) of the test No. 24,the number of white points (aggregation points of Ag) occurred was about10, and very small. Whereas, almost no increase in sheet resistancevalue due to the high-temperature high-humidity test was observable.

The electromagnetic-shielding Ag alloy film-formed products (Ag alloyfilm composition: Ag—Bi, or Sb—Au, Cu, or Pd) of the test Nos. 25 to 34are in accordance with Example 2-2 of the present invention. Table 13indicates as follows. As for these Ag alloy film-formed products, thenumber of white points (aggregation points of Ag) occurred is smallerthan with the Ag alloy film-formed product of the test No. 24, and thenumber of white points occurred decreases with an increase in amount ofAu, Cu, or Pd to be added.

Incidentally, in Examples 2-1 and 2-2 described above, Bi and Sb areeach singly added. However, also when they are added at the same time,the results of the same tendencies as with Examples 2-1 and 2-2 areobtainable. Whereas, in Example 2-2, for Cu, Au, Pd, Rh, Ru, Ir, and Pt,Au, Cu, and Pd are each singly added. However, also when these aresimultaneously added, the results of the same tendencies as with Example2 are obtainable. Whereas, also both in the case where elements (Rh, Ru,Ir, and Pt) other than Au, Cu, and Pd are each singly added, and in thecase where these are simultaneously added, the results of the sametendencies as with Example 2 are obtainable.

Example 2-3, Comparative Example 2-3

Using a target containing ITO as a main component, an ITO film wasdeposited with a thickness of 40 nm on a 70 μm-thick polyethyleneterephthalate (PET) film by a high-frequency sputtering process (underan Ar gas atmosphere). Then, using an Ag-0.5 at % Bi target (below,referred to as 0.5 Bi-T), an Ag—Bi alloy film was deposited with athickness of 15 nm. Further, another ITO film was deposited with athickness of 40 nm by a sputtering process. The multilayered film[below, referred to as a three-layered film of ITO/Ag—Bi alloy film(using 0.5 Bi-T, film thickness 15 nm)/ITO] was subjected to compositionanalysis in the direction of film thickness by XPS while being etchedfrom the surface by an Ar ion beam. As a result, it was observed that Biwas concentrated at the interface between the ITO film of the outermostlayer (the layer most distant from the PET film) and the Ag—Bi alloyfilm. Further, it was observed from the narrow-range spectrum of theconcentrated Bi that Bi was oxidized.

On the other hand, a multilayered film deposited using the one of atarget composition of Ag-1.5 at % Bi (below, referred to as 1.5 Bi-T)for the Ag—Bi alloy film with the film thickness of each layer and thenumber of layers being the same as in the foregoing multilayered film,[below, referred to as a three-layered film of ITO/Ag—Bi alloy film(using 1.5 Bi-T, film thickness 15 nm)/ITO], and a multilayered filmdeposited using the one of a target composition of Ag-2.0 at % Bi(below, referred to as 2.0 Bi-T) [below, referred to as a three-layeredfilm of ITO/Ag—Bi alloy film (using 2.0 Bi-T, film thickness 15 nm)/ITO]were also manufactured. Whereas, a multilayered film obtained by usingan Ag-1 at % Pd alloy film for the Ag—Bi alloy film in the foregoingdeposition, [below, referred to as a three-layered film of ITO/Ag-1% Pdalloy film (film thickness 15 nm)/ITO] (the film in accordance withComparative Example) was deposited. Further, a multilayered filmobtained by setting only the thickness of the Ag—Bi alloy film depositedusing 0.5 Bi-T (Ag-0.5 at % Bi target) at 2 nm in the foregoingdeposition [below, referred to as a three-layered film of ITO/Ag—Bialloy film (using 0.5 Bi-T, film thickness 2 nm)/ITO] was manufactured.

As for the five kinds of films manufactured in this manner, namely,

(1) Three-layered film of ITO/Ag—Bi alloy film (using 0.5 Bi-T, filmthickness 15 nm)/ITO;

(2) Three-layered film of ITO/Ag—Bi alloy film (using 1.5 Bi-T, filmthickness 15 nm)/ITO;

(3) Three-layered film of ITO/Ag—Bi alloy film (using 2.0 Bi-T, filmthickness 15 nm)/ITO;

(4) Three-layered film of ITO/Ag-1% Pd alloy film (film thickness 15nm)/ITO; and

(5) Three-layered film of ITO/Ag—Bi alloy film (using 0.5 Bi-T, filmthickness 2 nm)/ITO,

these were respectively immersed in salt water with a concentration of0.5 mol/L, to examine the aggregation degree of Ag through opticalmicroscope observation (magnification: 200 times).

As a result, in the film of (4), i.e., the three-layered film ofITO/Ag-1% Pd alloy film (film thickness 15 nm)/ITO (the film inaccordance with Comparative Example), white points indicating theaggregation of Ag started to occur on the surface in 75-hour immersion.In contrast, in the films of (1) to (3), i.e., the three-layered film ofITO/Ag—Bi alloy film (using 0.5 Bi-T, film thickness 15 nm)/ITO [thefilm in accordance with Example of the present invention], thethree-layered film of ITO/Ag—Bi alloy film (using 1.5 Bi-T, filmthickness 15 nm)/ITO [the film in accordance with Example of the presentinvention], and the three-layered film of ITO/Ag—Bi alloy film (using2.0 Bi-T, film thickness 15 nm)/ITO [the film in accordance with Exampleof the present invention], no change was observed at all even after150-hour immersion, and excellent salt water immersion resistance wasshown. Incidentally, all of the films of (1) to (3), and the film of (4)are equal in film thickness of the alloy film (film thickness 15 nm).

As for the film of (5), i.e., the three-layered film of ITO/Ag—Bi alloyfilm (using 0.5 Bi-T, film thickness 2 nm)/ITO, white points indicatingthe aggregation of Ag started to occur on the surface in 60-hourimmersion. Thus, it was inferior in salt water immersion resistance tothe film of (1). This is because the thickness of the Ag—Bi alloy filmis small (film thickness 2 nm). Thus, for the film of (5), the thicknessof the Ag—Bi alloy film is as thin as 2 nm. Still, as compared with thefilm of (4) in which the thickness of the Ag-1% Pd alloy film is 15 nm,which is larger than this [three-layered film of ITO/Ag-1% Pd alloy film(film thickness 15 nm)/ITO], the length of time until when white pointsindicating the aggregation start to occur on the surface is roughlyequal, and the salt water immersion resistance is not largely different,and roughly the same.

When the film is immersed in salt water (concentration 0.5 mol/L) asdescribed above, for the film of (5) [three-layered film of ITO/Ag—Bialloy film (using 0.5 Bi-T, film thickness 2 nm)/ITO], white pointsindicating the aggregation start to occur in 60 hours. Therefore, evenwith the Ag—Bi alloy film, when the film thickness is as small as 2 nm,it may be impossible to obtain a desirable salt water immersionresistance. In such a case, the thickness of the Ag—Bi alloy film isdesirably set at 3 nm or more.

Example 2-4, Comparative Example 2-4

On a 70 μm-thick PET (polyethylene phthalate) film, deposition wascarried out in the order of ITO film/Ag—Bi alloy film/ITO film/Ag—Bialloy film/ITO film/Ag—Bi alloy film/ITO film by a sputtering process.Thus, a multilayered film of ITO films and Ag—Bi alloy films wasdeposited. At this step, for manufacturing of the Ag—Bi alloy films, atarget of composition of Ag-0.25 at % Bi (below, referred to as 0.25Bi-T) was used. Further, deposition was carried out so that the filmthicknesses of respective layers are 20 nm for the ITO films and 10 nmfor the Ag—Bi alloy films. The multilayered film [below, referred to asa seven-layered film of ITO/Ag—Bi alloy film (using 0.25 Bi-T, filmthickness 10 nm)] was subjected to composition analysis in the directionof film thickness by XPS while being etched from the surface by an Arion beam. As a result, it was observed that Bi was concentrated at theinterface between the ITO film of the outermost layer (the layer mostdistant from the PET film) and the Ag—Bi alloy film. Further, it wasobserved from the narrow-range spectrum of the concentrated Bi that Biwas oxidized.

On the other hand, a multilayered film obtained by substituting an Ag-1at % Pd-1.7 at % Cu alloy film for the portion of the Ag—Bi alloy filmwith the film thickness of each layer and the number of layers being thesame as in the foregoing multilayered film, [below, referred to as aseven-layered film of ITO/Ag-1% Pd-1.7% Cu alloy film (film thickness 10nm) (a film in accordance with Comparative Example) was manufactured.

As for the two kinds of films manufactured in this manner, namely,

(a) Seven-layered film of ITO/Ag—Bi alloy film (using 0.25 Bi-T, filmthickness 10 nm); and

(b) Seven-layered film of ITO/Ag-1% Pd-1.7% Cu alloy film (filmthickness 10 nm)

these were respectively immersed in salt water with a concentration of0.5 mol/L, to examine the aggregation degree of Ag through opticalmicroscope observation (magnification: 200 times).

As a result, for the film of (b), i.e., the seven-layered film ofITO/Ag-1% Pd-1.7% Cu alloy film (film thickness 10 nm) (the film inaccordance with Comparative Example), white points indicating theaggregation of Ag started to occur on the surface in 40-hour immersion.In contrast, the film of (a), i.e., the seven-layered film of ITO/Ag—Bialloy film (using 0.25 Bi-T, film thickness 10 nm) [the film inaccordance with Example of the present invention], no change wasobserved at all even after 100-hour immersion, and excellent salt waterimmersion resistance was shown. Incidentally, all of the films of (a)and (b) are equal in film thickness of the alloy film (film thickness 10nm).

[see Tables 11-13]

Example 3-1

On a pure Ag target, 5 mm×5 mm Bi or Sb metal chips were placed. By DCmagnetron sputtering, a 100 nm-thick sample of each composition shown intest Nos. 1 to 12 of Table 1 was formed on a glass plate. As for thecomposition of each thin film, separately, samples with a film thicknessof 1 μm were manufactured under the same conditions. Thus, theidentification of each composition was carried out with an ICP-massspectrometry (SPQ-8000 manufactured by Seiko Instrument Inc.).Specifically, 100 mg or more of the sample was dissolved in a solutionof sulfuric acid:pure water=1:1 as a pretreatment. The resultingsolution was heated on a 200° C. hot plate, and it was checked that thesample was completely dissolved. Then, the solution was cooled andanalyzed. The target size was φ100 mm, and the size of the glasssubstrate was φ50 mm. The main deposition conditions are as follows.Reached degree of vacuum: 6.67×10⁻⁴ Pa, Ar gas pressure duringdeposition: 0.267 Pa, Substrate temperature: 25° C., and Distancebetween target-substrate: 55 mm.

Immediately after deposition, the reflectance of each sample wasmeasured by means of a visible-UV spectrophotometer (manufactured byShimadzu Corp.). Further, each reflectance after an environmental test(temperature 80° C., relative humidity 90%, and time 48 h) of thesesamples was measured by means of the spectrophotometer. Then, the amountof change in reflectance before and after the environmental test wasevaluated. Further, the surface roughnesses before and after theenvironmental test were measured by means of an atomic force microscope(AFM). Then, the amount of change in surface roughness before and afterthe environmental test was evaluated. Further, a salt immersion test(NaCl: 0.05 mol/L, 15 min) was carried out. Then, the degree ofdiscoloration of the optical reflective film and the occurrence ornon-occurrence of peeling of the optical reflective film from thesubstrate were visually observed to evaluate the NaCl resistance.

Comparative Example 3-1

Ag alloy thin films of the compositions shown in the test Nos. 13 to 16of Table 1 were manufactured under the same deposition conditions aswith Example 3-1, except that as the metal chips to be placed on thepure Ag target, Nd, In, Nb, or Sn was used in place of Bi or Sb ofExample 3-1. The same evaluations as with Example 3-1 were carried out.

The evaluation results on Example 3-1 and Comparative Example 3-1 areshown together in Table 14. As shown in Example 3-1 of Table 14, it isindicated that the amount of change in reflectance and the amount ofchange in surface roughness before and after the environmental test areremarkably suppressed by the addition of Bi or Sb (test Nos. 2 to 12) ascompared with the pure Ag thin film (test No. 1). As for the amount ofBi or Sb to be added, even when it is 0.01 at %, the effects areobservable (test Nos. 2 and 8), and particularly, when it is 0.05 at %or more, the effect is large (test Nos. 3 to 7 and 9 to 12). Further, itis indicated that, also after the salt immersion test, discolorationsuch as turning yellow, and peeling of the optical reflective film fromthe substrate are eliminated by the addition of Bi or Sb, and thatfavorable durabilities are shown.

In contrast, as shown in Comparative Example 3-1 of Table 14, Ag—Ndshows favorable results with respect to the suppression of the amount ofchange in reflectance before and after the environmental test, but hasno NaCl resistance (test No. 13). Whereas, Ag—In, Ag—Nb, and Ag—Sn havevery low suppression effects on the amount of change in surfaceroughness (test Nos. 14 to 16).

Example 3-2

Using a composite target formed by locating 5 mm×5 mm metal chips of Bi,Cu, Au, Nd, or Y on a pure Ag or Ag-0.2% Sb target, each sample wasmanufactured under the same deposition conditions as with Example 3-1.The same evaluations as with Example 3-1 were carried out on thesesamples. The results are shown Table 15. Incidentally, the test Nos. 1and 4 in Table 14 are reshown in Table 15 for comparison.

It is indicated that the surface roughness and the amount of changethereof are further improved by further adding Nd or Y to Ag—Bi (testNos. 17 and 18). Whereas, it is indicated as follows. When Cu or Au isfurther added to Ag—Bi or Ag—Sb, the further improvement effects of thesurface roughness are not produced. However, the effects of reducing theamount of change in reflectance are produced (test Nos. 19 to 24).

[see Tables 14, 15]

Example 4 Comparison Between the Bi Content in a Sputtering Target andthe Bi Content in a Thin Film

For comparison of the Bi content between in the sputtering target and inthe thin film deposited using this, Ag base alloy thin films weredeposited using the sputtering targets having the respectivecompositions shown in Table 16. With a sputtering process (under an Argas atmosphere), each Ag alloy film (Ag—Bi system alloy film) wasdeposited so that the film thickness was controlled to about 15 nm on atransparent substrate (colorless float glass, board thickness: 3 mm,size: 2 cm×4 cm). At this step, as the sputtering target, amelt-produced target comprising a Bi-containing Ag base alloy(manufactured by a vacuum dissolution process) was used. Incidentally,the Bi content in the melt-produced target was confirmed by measurement(analysis).

10 mg or more of the Ag base alloy portion of each thin film obtainedwas used as a sample, and this was dissolved in a solution of sulfuricacid: pure water=1:1. Subsequently, the resulting solution was heated ona 200° C. hot plate, and it was checked that the sample was completelydissolved. Then, the solution was cooled. Then, the amount of Bicontained in the thin film was measured by means of an ICP-massspectrometry (SPQ-8000 manufactured by Seiko Instrument Inc.). Theresults are shown in Table 16.

[see Table 16]

Table 16 indicates that the Bi content in the Ag alloy film is lowerthan the Bi content in the sputtering target. The Bi content in thesputtering target for obtaining an Ag alloy film having a desirable Bicontent is required to be determined in consideration of therelationship of the Bi content between in the sputtering target and inthe thin film deposited using this.

TABLE 1 Results of thermal conductivity measurement Sam- Thermal pleconductivity High thermal No. Composition [W/(m · K)] conductivity 1Pure Ag 320 ◯ 2 Ag—0.005at % Bi Alloy 319 ◯ 3 Ag—0.2at % Bi Alloy 296 ◯4 Ag—0.4at % Bi Alloy 271 ◯ 5 Ag—0.6at % Bi Alloy 247 X 6 Ag—0.005at %Sb Alloy 319 ◯ 7 Ag—0.2at % Sb Alloy 292 ◯ 8 Ag—0.4at % Sb Alloy 264 ◯ 9Ag—0.6at % Sb Alloy 236 X 10 Ag—0.2at % Bi—0.01at % Nd Alloy 296 ◯ 11Ag—0.2at % Bi—0.1at % Nd Alloy 294 ◯ 12 Ag—0.2at % Bi—0.5at % Nd Alloy287 ◯ 13 Ag—0.2at % Bi—2at % Nd Alloy 260 ◯ 14 Ag—0.2at % Bi—3at % NdAlloy 242 X 15 Ag—0.2at % Bi—0.01at % Y Alloy 296 ◯ 16 Ag—0.2at %Bi—0.1at % Y Alloy 294 ◯ 17 Ag—0.2at % Bi—0.5at % Y Alloy 288 ◯ 18Ag—0.2at % Bi—2at % Y Alloy 262 ◯ 19 Ag—0.2at % Bi—3at % Y Alloy 245 X20 Ag—0.2at % Sb—0.01at % Nd Alloy 292 ◯ 21 Ag—0.2at % Sb—0.1at % NdAlloy 290 ◯ 22 Ag—0.2at % Sb—0.5at % Nd Alloy 283 ◯ 23 Ag—0.2at % Sb—2at% Nd Alloy 256 ◯ 24 Ag—0.2at % Sb—3at % Nd Alloy 238 X 25 Ag—0.2at %Sb—0.01at % Y Alloy 292 ◯ 26 Ag—0.2at % Sb—0.1at % Y Alloy 290 ◯ 27Ag—0.2at % Sb—0.5at % Y Alloy 284 ◯ 28 Ag—0.2at % Sb—2at % Y Alloy 258 ◯29 Ag—0.2at % Sb—3at % Y Alloy 241 X

TABLE 2 Results of thermal conductivity measurement Sam- Thermal pleconductivity High thermal No. Composition [W/(m · K)] conductivity 1Pure Ag 320 ◯ 30 Ag—0.2at % Bi—0.01at % Cu Alloy 296 ◯ 31 Ag—0.2at %Bi—0.1at % Cu Alloy 295 ◯ 32 Ag—0.2at % Bi—0.5at % Cu Alloy 290 ◯ 33Ag—0.2at % Bi—2at % Cu Alloy 260 ◯ 34 Ag—0.2at % Bi—3at % Cu Alloy 248 X35 Ag—0.2at % Bi—0.01at % Au Alloy 296 ◯ 36 Ag—0.2at % Bi—0.1at % AuAlloy 295 ◯ 37 Ag—0.2at % Bi—0.5at % Au Alloy 290 ◯ 38 Ag—0.2at % Bi—2at% Au Alloy 262 ◯ 39 Ag—0.2at % Bi—3at % Au Alloy 251 X 40 Ag—0.2at %Sb—0.01at % Cu Alloy 292 ◯ 41 Ag—0.2at % Sb—0.1at % Cu Alloy 291 ◯ 42Ag—0.2at % Sb—0.5at % Cu Alloy 286 ◯ 43 Ag—0.2at % Sb—2at % Cu Alloy 256◯ 44 Ag—0.2at % Sb—3at % Cu Alloy 244 X 45 Ag—0.2at % Sb—0.01at % AuAlloy 292 ◯ 46 Ag—0.2at % Sb—0.1at % Au Alloy 291 ◯ 47 Ag—0.2at %Sb—0.5at % Au Alloy 286 ◯ 48 Ag—0.2at % Sb—2at % Au Alloy 258 ◯ 49Ag—0.2at % Sb—3at % Au Alloy 247 X 50 Ag—0.2at % Bi—0.5at % Nd—0.5at 281◯ % Cu Alloy 51 Ag—0.2at % Bi—0.5at % Nd—0.5at 281 ◯ % Au Alloy 52Ag—0.2at % Bi—0.5at % Y—0.5at 282 ◯ % Cu Alloy 53 Ag—0.2at % Bi—0.5at %Y—0.5at 282 ◯ % Au Alloy 54 Ag—0.2at % Sb—0.5at % Nd—0.5at 277 ◯ % CuAlloy 55 Ag—0.2at % Sb—0.5at % Nd—0.5at 277 ◯ % Au Alloy 56 Ag—0.2at %Sb—0.5at % Y—0.5at 278 ◯ % Cu Alloy 57 Ag—0.2at % Sb—0.5at % Y—0.5at 278◯ % Au Alloy 58 Ag—0.2at % Si Alloy 265 ◯ 59 Ag—0.2at % Sn Alloy 248 X

TABLE 3 Results of reflectance measurement Reflectance relative to PureAg [%] Sam- Wave- Wave- High ple length length reflec- No. Composition405 nm 650 nm tance 1 Pure Ag 90.8 92.5 ◯ 2 Ag—0.005at % Bi Alloy 90.792.5 ◯ 3 Ag—0.2at % Bi Alloy 86.2 90.8 ◯ 4 Ag—0.4at % Bi Alloy 81.6 89.1◯ 5 Ag—0.6at % Bi Alloy 77.0 87.4 X 6 Ag—0.005at % Sb Alloy 90.7 92.5 ◯7 Ag—0.2at % Sb Alloy 86.1 90.7 ◯ 8 Ag—0.4at % Sb Alloy 81.4 88.9 ◯ 9Ag—0.6at % Sb Alloy 76.7 87.1 X 10 Ag—0.2at % Bi—0.01at % Nd Alloy 86.290.8 ◯ 11 Ag—0.2at % Bi—0.1at % Nd Alloy 85.9 90.7 ◯ 12 Ag—0.2at %Bi—0.5at % Nd Alloy 84.8 90.3 ◯ 13 Ag—0.2at % Bi—2at % Nd Alloy 80.788.6 ◯ 14 Ag—0.2at % Bi—3at % Nd Alloy 78.0 87.5 X 15 Ag—0.2at %Bi—0.01at % Y Alloy 86.2 90.8 ◯ 16 Ag—0.2at % Bi—0.1at % Y Alloy 85.990.7 ◯ 17 Ag—0.2at % Bi—0.5at % Y Alloy 84.7 90.2 ◯ 18 Ag—0.2at % Bi—2at% Y Alloy 80.3 88.4 ◯ 19 Ag—0.2at % Bi—3at % Y Alloy 77.4 87.2 X 20Ag—0.2at % Sb—0.01at % Nd Alloy 86.1 90.7 ◯ 21 Ag—0.2at % Sb—0.1at % NdAlloy 85.8 90.6 ◯ 22 Ag—0.2at % Sb—0.5at % Nd Alloy 84.7 90.2 ◯ 23Ag—0.2at % Sb—2at % Nd Alloy 80.6 88.5 ◯ 24 Ag—0.2at % Sb—3at % Nd Alloy77.9 87.4 X 25 Ag—0.2at % Sb—0.01at % Y Alloy 86.1 90.7 ◯ 26 Ag—0.2at %Sb—0.1at % Y Alloy 85.8 90.6 ◯ 27 Ag—0.2at % Sb—0.5at % Y Alloy 84.690.1 ◯ 28 Ag—0.2at % Sb—2at % Y Alloy 80.2 88.3 ◯ 29 Ag—0.2at % Sb—3at %Y Alloy 77.3 87.1 X

TABLE 4 Results of reflectance measurement Reflectance relative to PureAg [%] Sam- Wave- Wave- High ple length length reflec- No. Composition405 nm 650 nm tance 1 Pure Ag 90.8 92.5 ◯ 30 Ag—0.2at % Bi—0.01at % CuAlloy 86.2 90.8 ◯ 31 Ag—0.2at % Bi—0.1at % Cu Alloy 86.0 90.7 ◯ 32Ag—0.2at % Bi—0.5at % Cu Alloy 85.3 90.4 ◯ 33 Ag—0.2at % Bi—2at % CuAlloy 81.0 88.3 ◯ 34 Ag—0.2at % Bi—4at % Cu Alloy 79.3 87.5 X 35Ag—0.2at % Bi—0.01at % Au Alloy 86.2 90.8 ◯ 36 Ag—0.2at % Bi—0.1at % AuAlloy 86.0 90.7 ◯ 37 Ag—0.2at % Bi—0.5at % Au Alloy 85.4 90.4 ◯ 38Ag—0.2at % Bi—3at % Au Alloy 81.5 88.5 ◯ 39 Ag—0.2at % Bi—4at % Au Alloy79.9 87.7 X 40 Ag—0.2at % Sb—0.01at % Cu Alloy 86.1 90.7 ◯ 41 Ag—0.2at %Sb—0.1at % Cu Alloy 85.9 90.6 ◯ 42 Ag—0.2at % Sb—0.5at % Cu Alloy 85.290.3 ◯ 43 Ag—0.2at % Sb—3at % Cu Alloy 80.9 88.2 ◯ 44 Ag—0.2at % Sb—4at% Cu Alloy 79.2 87.4 X 45 Ag—0.2at % Sb—0.01at % Au Alloy 86.1 90.7 ◯ 46Ag—0.2at % Sb—0.1at % Au Alloy 85.9 90.6 ◯ 47 Ag—0.2at % Sb—0.5at % AuAlloy 85.3 90.3 ◯ 48 Ag—0.2at % Sb—3at % Au Alloy 81.4 88.4 ◯ 49Ag—0.2at % Sb—4at % Au Alloy 79.8 87.6 X 50 Ag—0.2at % Bi—0.5at %Nd—0.5at 84.0 89.8 ◯ % Cu Alloy 51 Ag—0.2at % Bi—0.5at % Nd—0.5at 84.089.9 ◯ % Au Alloy 52 Ag—0.2at % Bi—0.5at % Y—0.5at 83.9 89.8 ◯ % CuAlloy 53 Ag—0.2at % Bi—0.5at % Y—0.5at 83.9 89.8 ◯ % Au Alloy 54Ag—0.2at % Sb—0.5at % Nd—0.5at 83.9 89.7 ◯ % Cu Alloy 55 Ag—0.2at %Sb—0.5at % Nd—0.5at 83.9 89.8 ◯ % Au Alloy 56 Ag—0.2at % Sb—0.5at %Y—0.5at 83.8 89.7 ◯ % Cu Alloy 57 Ag—0.2at % Sb—0.5at % Y—0.5at 83.889.7 ◯ % Au Alloy 58 Ag—0.2at % Si Alloy 85.5 90.3 ◯ 59 Ag—0.2at % SnAlloy 85.0 89.9 ◯

TABLE 5 Results of durability (thermal stability) evaluation Change inreflectance before and after high temperature high humidity test [%]Sample Wavelength Wavelength High No. Composition 405 nm 650 nmdurability 1 Pure Ag −27.3 −3.0 X 2 Ag—0.005at % Bi Alloy −1.4 −0.8 ◯ 3Ag—0.2at % Bi Alloy −0.7 −0.3 ◯ 4 Ag—0.4at % Bi Alloy −0.5 −0.2 ◯ 5Ag—0.6at % Bi Alloy −0.3 −0.1 ◯ 6 Ag—0.005at % Sb Alloy −1.6 −0.9 ◯ 7Ag—0.2at % Sb Alloy −0.8 −0.4 ◯ 8 Ag—0.4at % Sb Alloy −0.6 −0.3 ◯ 9Ag—0.6at % Sb Alloy −0.4 −0.2 ◯ 10 Ag—0.2at % Bi—0.01at % Nd Alloy −0.6−0.2 ◯ 11 Ag—0.2at % Bi—0.1at % Nd Alloy −0.5 −0.1 ◯ 12 Ag—0.2at %Bi—0.5at % Nd Alloy −0.3 −0.1 ◯ 13 Ag—0.2at % Bi—2at % Nd Alloy 0.0 0.0◯ 14 Ag—0.2at % Bi—3at % Nd Alloy 0.0 0.0 ◯ 15 Ag—0.2at % Bi—0.01at % YAlloy −0.6 −0.2 ◯ 16 Ag—0.2at % Bi—0.1at % Y Alloy −0.5 −0.1 ◯ 17Ag—0.2at % Bi—0.5at % Y Alloy −0.4 −0.1 ◯ 18 Ag—0.2at % Bi—2at % Y Alloy0.0 0.0 ◯ 19 Ag—0.2at % Bi—3at % Y Alloy 0.0 0.0 ◯ 20 Ag—0.2at %Sb—0.01at % Nd Alloy −0.7 −0.3 ◯ 21 Ag—0.2at % Sb—0.1at % Nd Alloy −0.6−0.2 ◯ 22 Ag—0.2at % Sb—0.5at % Nd Alloy −0.4 −0.2 ◯ 23 Ag—0.2at %Sb—2at % Nd Alloy 0.0 0.0 ◯ 24 Ag—0.2at % Sb—3at % Nd Alloy 0.0 0.0 ◯ 25Ag—0.2at % Sb—0.01at % Y Alloy −0.7 −0.3 ◯ 26 Ag—0.2at % Sb—0.1at % YAlloy −0.6 −0.2 ◯ 27 Ag—0.2at % Sb—0.5at % Y Alloy −0.5 −0.2 ◯ 28Ag—0.2at % Sb—2at % Y Alloy 0.0 0.0 ◯ 29 Ag—0.2at % Sb—3at % Y Alloy 0.00.0 ◯

TABLE 6 Results of durability (thermal stability) evaluation Change inreflectance before and after high temperature high humidity test [%]Sample Wavelength Wavelength High No. Composition 405 nm 650 nmdurability 1 Pure Ag −27.3 −3.0 X 30 Ag—0.2at % Bi—0.01at % Cu Alloy−0.6 −0.2 ◯ 31 Ag—0.2at % Bi—0.1at % Cu Alloy −0.5 −0.1 ◯ 32 Ag—0.2at %Bi—0.5at % Cu Alloy −0.4 −0.1 ◯ 33 Ag—0.2at % Bi—3at % Cu Alloy 0.0 0.0◯ 34 Ag—0.2at % Bi—4at % Cu Alloy 0.0 0.0 ◯ 35 Ag—0.2at % Bi—0.01at % AuAlloy −0.6 −0.2 ◯ 36 Ag—0.2at % Bi—0.1at % Au Alloy −0.5 −0.1 ◯ 37Ag—0.2at % Bi—0.5at % Au Alloy −0.4 −0.1 ◯ 38 Ag—0.2at % Bi—3at % AuAlloy 0.0 0.0 ◯ 39 Ag—0.2at % Bi—4at % Au Alloy 0.0 0.0 ◯ 40 Ag—0.2at %Sb—0.01at % Cu Alloy −0.7 −0.3 ◯ 41 Ag—0.2at % Sb—0.1at % Cu Alloy −0.6−0.2 ◯ 42 Ag—0.2at % Sb—0.5at % Cu Alloy −0.4 −0.1 ◯ 43 Ag—0.2at %Sb—2at % Cu Alloy 0.0 0.0 ◯ 44 Ag—0.2at % Sb—4at % Cu Alloy 0.0 0.0 ◯ 45Ag—0.2at % Sb—0.01at % Au Alloy −0.7 −0.3 ◯ 46 Ag—0.2at % Sb—0.1at % AuAlloy −0.5 −0.2 ◯ 47 Ag—0.2at % Sb—0.5at % Au Alloy −0.3 −0.1 ◯ 48Ag—0.2at % Sb—3at % Au Alloy 0.0 0.0 ◯ 49 Ag—0.2at % Sb—4at % Au Alloy0.0 0.0 ◯ 50 Ag—0.2at % Bi—0.5at % Nd—0.5at % Cu Alloy 0.0 0.0 ◯ 51Ag—0.2at % Bi—0.5at % Nd—0.5at % Au Alloy 0.0 0.0 ◯ 52 Ag—0.2at %Bi—0.5at % Y—0.5at % Cu Alloy 0.0 0.0 ◯ 53 Ag—0.2at % Bi—0.5at % Y—0.5at% Au Alloy 0.0 0.0 ◯ 54 Ag—0.2at % Sb—0.5at % Nd—0.5at % Cu Alloy 0.00.0 ◯ 55 Ag—0.2at % Sb—0.5at % Nd—0.5at % Au Alloy 0.0 0.0 ◯ 56 Ag—0.2at% Sb—0.5at % Y—0.5at % Cu Alloy 0.0 0.0 ◯ 57 Ag—0.2at % Sb—0.5at %Y—0.5at % Au Alloy 0.0 0.0 ◯ 58 Ag—0.2at % Si Alloy −19.9 −2.1 X 59Ag—0.2at % Sn Alloy −18.4 −1.8 X

TABLE 7 Change in appearance after salt immersion test of Ag-based thinfilm Change in Sam- appearance ple after salt High No. Compositionimmersion test durability 1 Pure Ag Yes X 2 Ag—0.005at % Bi Alloy No ◯ 3Ag—0.2at % Bi Alloy No ◯ 4 Ag—0.4at % Bi Alloy No ◯ 5 Ag—0.6at % BiAlloy No ◯ 6 Ag—0.005at % Sb Alloy No ◯ 7 Ag—0.2at % Sb Alloy No ◯ 8Ag—0.4at % Sb Alloy No ◯ 9 Ag—0.6at % Sb Alloy No ◯ 10 Ag—0.2at %Bi—0.01at % Nd Alloy No ◯ 11 Ag—0.2at % Bi—0.1at % Nd Alloy No ◯ 12Ag—0.2at % Bi—0.5at % Nd Alloy No ◯ 13 Ag—0.2at % Bi—2at % Nd Alloy No ◯14 Ag—0.2at % Bi—3at % Nd Alloy No ◯ 15 Ag—0.2at % Bi—0.01at % Y AlloyNo ◯ 16 Ag—0.2at % Bi—0.1at % Y Alloy No ◯ 17 Ag—0.2at % Bi—0.5at % YAlloy No ◯ 18 Ag—0.2at % Bi—2at % Y Alloy No ◯ 19 Ag—0.2at % Bi—3at % YAlloy No ◯ 20 Ag—0.2at % Sb—0.01at % Nd Alloy No ◯ 21 Ag—0.2at %Sb—0.1at % Nd Alloy No ◯ 22 Ag—0.2at % Sb—0.5at % Nd Alloy No ◯ 23Ag—0.2at % Sb—2at % Nd Alloy No ◯ 24 Ag—0.2at % Sb—3at % Nd Alloy No ◯25 Ag—0.2at % Sb—0.01at % Y Alloy No ◯ 26 Ag—0.2at % Sb—0.1at % Y AlloyNo ◯ 27 Ag—0.2at % Sb—0.5at % Y Alloy No ◯ 28 Ag—0.2at % Sb—2at % YAlloy No ◯ 29 Ag—0.2at % Sb—3at % Y Alloy No ◯

TABLE 8 Change in appearance after salt immersion test of Ag-based thinfilm Change in Sam- appearance ple after salt High No. Compositionimmersion test durability 1 Pure Ag Yes X 30 Ag—0.2at % Bi—0.01at % CuAlloy No ◯ 31 Ag—0.2at % Bi—0.1at % Cu Alloy No ◯ 32 Ag—0.2at % Bi—0.5at% Cu Alloy No ◯ 33 Ag—0.2at % Bi—3at % Cu Alloy No ◯ 34 Ag—0.2at %Bi—4at % Cu Alloy No ◯ 35 Ag—0.2at % Bi—0.01at % Au Alloy No ◯ 36Ag—0.2at % Bi—0.1at % Au Alloy No ◯ 37 Ag—0.2at % Bi—0.5at % Au Alloy No◯ 38 Ag—0.2at % Bi—3at % Au Alloy No ◯ 39 Ag—0.2at % Bi—4at % Au AlloyNo ◯ 40 Ag—0.2at % Sb—0.01at % Cu Alloy No ◯ 41 Ag—0.2at % Sb—0.1at % CuAlloy No ◯ 42 Ag—0.2at % Sb—0.5at % Cu Alloy No ◯ 43 Ag—0.2at % Sb—3at %Cu Alloy No ◯ 44 Ag—0.2at % Sb—4at % Cu Alloy No ◯ 45 Ag—0.2at %Sb—0.01at % Au Alloy No ◯ 46 Ag—0.2at % Sb—0.1at % Au Alloy No ◯ 47Ag—0.2at % Sb—0.5at % Au Alloy No ◯ 48 Ag—0.2at % Sb—3at % Au Alloy No ◯49 Ag—0.2at % Sb—4at % Au Alloy No ◯ 50 Ag—0.2at % Bi—0.5at % Nd—0.5atNo ◯ % Cu Alloy 51 Ag—0.2at % Bi—0.5at % Nd—0.5at No ◯ % Au Alloy 52Ag—0.2at % Bi—0.5at % Y—0.5at No ◯ % Cu Alloy 53 Ag—0.2at % Bi—0.5at %Y—0.5at No ◯ % Au Alloy 54 Ag—0.2at % Sb—0.5at % Nd—0.5at No ◯ % CuAlloy 55 Ag—0.2at % Sb—0.5at % Nd—0.5at No ◯ % Au Alloy 56 Ag—0.2at %Sb—0.5at % Y—0.5at No ◯ % Cu Alloy 57 Ag—0.2at % Sb—0.5at % Y—0.5at No ◯% Au Alloy 58 Ag—0.2at % Si Alloy Yes X 59 Ag—0.2at % Sn Alloy Yes X

TABLE 9 Average roughness before and after high temperature highhumidity test of Ag-based thin film Average roughness before and afterhigh temperature high humidity test [nm] Sample No. Composition Beforetest After test High durability 1 Pure Ag 4.18 7.33 X 2 Ag—0.005at % BiAlloy 0.63 0.93 ◯ 3 Ag—0.2at % Bi Alloy 0.58 0.61 ◯ 4 Ag—0.4at % BiAlloy 0.55 0.58 ◯ 5 Ag—0.6at % Bi Alloy 0.52 0.54 ◯ 6 Ag—0.005at % SbAlloy 0.65 0.95 ◯ 7 Ag—0.2at % Sb Alloy 0.58 0.63 ◯ 8 Ag—0.4at % SbAlloy 0.56 0.59 ◯ 9 Ag—0.6at % Sb Alloy 0.54 0.57 ◯ 10 Ag—0.2at %Bi—0.01at % Nd Alloy 0.58 0.60 ◯ 11 Ag—0.2at % Bi—0.1at % Nd Alloy 0.550.59 ◯ 12 Ag—0.2at % Bi—0.5at % Nd Alloy 0.52 0.56 ◯ 13 Ag—0.2at %Bi—2at % Nd Alloy 0.45 0.48 ◯ 14 Ag—0.2at % Bi—3at % Nd Alloy 0.44 0.48◯ 15 Ag—0.2at % Bi—0.01at % Y Alloy 0.57 0.60 ◯ 16 Ag—0.2at % Bi—0.1at %Y Alloy 0.56 0.59 ◯ 17 Ag—0.2at % Bi—0.5at % Y Alloy 0.53 0.58 ◯ 18Ag—0.2at % Bi—2at % Y Alloy 0.47 0.53 ◯ 19 Ag—0.2at % Bi—3at % Y Alloy0.45 0.52 ◯ 20 Ag—0.2at % Sb—0.01at % Nd Alloy 0.58 0.62 ◯ 21 Ag—0.2at %Sb—0.1at % Nd Alloy 0.56 0.60 ◯ 22 Ag—0.2at % Sb—0.5at % Nd Alloy 0.530.58 ◯ 23 Ag—0.2at % Sb—2at % Nd Alloy 0.47 0.50 ◯ 24 Ag—0.2at % Sb—3at% Nd Alloy 0.47 0.49 ◯ 25 Ag—0.2at % Sb—0.01at % Y Alloy 0.58 0.63 ◯ 26Ag—0.2at % Sb—0.1at % Y Alloy 0.55 0.61 ◯ 27 Ag—0.2at % Sb—0.5at % YAlloy 0.54 0.60 ◯ 28 Ag—0.2at % Sb—2at % Y Alloy 0.46 0.54 ◯ 29 Ag—0.2at% Sb—3at % Y Alloy 0.45 0.53 ◯

TABLE 10 Average roughness before and after high temperature highhumidity test of Ag-based thin film Average roughness before and afterhigh temperature high humidity test [nm] Sample No. Composition Beforetest After test High durability 1 Pure Ag 4.18 7.33 X 30 Ag—0.2at %Bi—0.01at % Cu Alloy 0.59 0.93 ◯ 31 Ag—0.2at % Bi—0.1at % Cu Alloy 0.580.90 ◯ 32 Ag—0.2at % Bi—0.5at % Cu Alloy 0.56 0.86 ◯ 33 Ag—0.2at %Bi—3at % Cu Alloy 0.55 0.75 ◯ 34 Ag—0.2at % Bi—4at % Cu Alloy 0.54 0.73◯ 35 Ag—0.2at % Bi—0.01at % Au Alloy 0.59 0.94 ◯ 36 Ag—0.2at % Bi—0.1at% Au Alloy 0.57 0.89 ◯ 37 Ag—0.2at % Bi—0.5at % Au Alloy 0.56 0.84 ◯ 38Ag—0.2at % Bi—3at % Au Alloy 0.54 0.76 ◯ 39 Ag—0.2at % Bi—4at % Au Alloy0.53 0.75 ◯ 40 Ag—0.2at % Sb—0.01at % Cu Alloy 0.59 0.95 ◯ 41 Ag—0.2at %Sb—0.1at % Cu Alloy 0.58 0.91 ◯ 42 Ag—0.2at % Sb—0.5at % Cu Alloy 0.570.88 ◯ 43 Ag—0.2at % Sb—3at % Cu Alloy 0.56 0.78 ◯ 44 Ag—0.2at % Sb—4at% Cu Alloy 0.54 0.77 ◯ 45 Ag—0.2at % Sb—0.01at % Au Alloy 0.58 0.94 ◯ 46Ag—0.2at % Sb—0.1at % Au Alloy 0.58 0.90 ◯ 47 Ag—0.2at % Sb—0.5at % AuAlloy 0.57 0.86 ◯ 48 Ag—0.2at % Sb—3at % Au Alloy 0.57 0.79 ◯ 49Ag—0.2at % Sb—4at % Au Alloy 0.55 0.77 ◯ 50 Ag—0.2at % Bi—0.5at %Nd—0.5at % Cu Alloy 0.50 0.55 ◯ 51 Ag—0.2at % Bi—0.5at % Nd—0.5at % AuAlloy 0.51 0.56 ◯ 52 Ag—0.2at % Bi—0.5at % Y—0.5at % Cu Alloy 0.52 0.57◯ 53 Ag—0.2at % Bi—0.5at % Y—0.5at % Au Alloy 0.51 0.55 ◯ 54 Ag—0.2at %Sb—0.5at % Nd—0.5at % Cu Alloy 0.52 0.58 ◯ 55 Ag—0.2at % Sb—0.5at %Nd—0.5at % Au Alloy 0.53 0.60 ◯ 56 Ag—0.2at % Sb—0.5at % Y—0.5at % CuAlloy 0.52 0.59 ◯ 57 Ag—0.2at % Sb—0.5at % Y—0.5at % Au Alloy 0.54 0.59◯ 58 Ag—0.2at % Si Alloy 0.68 1.17 X 59 Ag—0.2at % Sn Alloy 0.79 1.25 X

TABLE 11 Evaluation results Sheet resistance (Ω/□) Salt immersion testAmount of High temperature high Before After Visible light DiscolorationTest element humidity test Ag aggregation Ag aggregation transmittance(turning No. Composition added (at %) (Ag aggregation test) test test(%) yellow) Peeling Comparative 1 Pure Ag — X 12 48 80 X ObservedExample 1 Example 1 2 Ag—Bi 0.01 Δ 12 23 80 Δ None 3 0.04 ◯ 13 16 79 ◯None 4 0.12 ◯ 16 16 79 ◯ None 5 0.19 ◯ 18 17 78 ◯ None 6 1.2 ◯ 20 20 76◯ None 7 5.1 ◯ 29 30 72 ◯ None 8 10.0 ◯ 41 41 43 ◯ None 9 Ag—Sb 0.009 Δ12 25 80 Δ None 10 0.05 ◯ 12 14 78 ◯ None 11 0.11 ◯ 13 13 77 ◯ None 120.22 ◯ 18 17 76 ◯ None 13 1.1 ◯ 23 21 73 ◯ None 14 4.9 ◯ 31 33 70 ◯ None15 10.0 ◯ 43 45 45 ◯ None

TABLE 12 Evaluation results Sheet resistance (Ω/□) Salt immersion testAmount of High temperature high Before After Visible light DiscolorationTest element humidity test Ag aggregation Ag aggregation transmittance(turning No. Composition added (at %) (Ag aggregation test) test test(%) yellow) Peeling Comparative 16 Ag—Nd 1.0 ◯ 13 14 77 X ObservedExample 1 17 Ag—In 0.40 X 14 35 76 Δ None 18 Ag—Nb 0.92 X 16 38 75 ΔObserved 19 Ag—Sn 0.88 X 16 42 76 X Observed 20 Ag—Cu 1.0 X 13 36 75 XNone 21 Ag—Al 0.9 X 16 47 63 X Observed 22 Ag—Zn 1.0 X 20 46 67 XObserved

TABLE 13 Evaluation results Amount High temperature Sheet resistance(Ω/□) of element high humidity test Before After Visible light Testadded (at %) Number of white Ag aggregation Ag aggregation transmittanceNo. Composition Bi/Sb Others spots generated test test (%) Comparative23 Ag — — 98 5 43 79 Example 2 Example 2 24 Ag—Bi 0.19 — 10 16 15 77 25Ag—Bi—Au 0.19 0.3 8 16 16 77 26 0.19 0.9 5 16 17 76 27 Ag—Bi—Cu 0.19 0.410 17 20 75 28 0.19 1.1 4 17 19 73 29 Ag—Bi—Pb 0.19 0.3 8 16 15 76 300.19 1.5 4 19 19 72 31 Ag—Sb—Au 0.21 3.0 0 17 16 68 32 0.21 10.0 0 26 2653 33 Ag—Sb—Cu 0.21 2.7 0 19 17 65 34 0.21 9.7 0 28 30 48

TABLE 14 Evaluation results Reflectance (%): Wavelength 400 nm Initialreflectance Surface roughness before After (nm) Amount of environ-environ- Before After Amount Salt immersion test element mental mentalAmount of environ- environ- of Electric Discoloration Test added testtest change mental mental change resistance (turning No. Composition (at%) [A] [B] [B − A] test [C] test [D] [D − C] (μΩcm) yellow) PeelingExample 1 1 Pure Ag — 90.8 63.5 −27.3 4.2 7.3 3.1 2.3 X Observed 2 Ag—Bi0.01 89.4 83.0 −5.4 2.1 2.8 0.7 2.5 Δ None 3 0.04 88.2 87.2 −1.0 0.921.01 0.09 2.6 ◯ None 4 0.19 86.2 85.4 −0.8 0.65 0.71 0.06 3.3 ◯ None 50.9 81.2 81.4 +0.2 0.64 0.65 0.01 7.0 ◯ None 6 2.0 74.3 73.8 −0.5 0.630.62 −0.01 14.8 ◯ None 7 3.1 62.3 62.4 +0.1 0.64 0.66 0.02 20.6 ◯ None 8Ag—Sb 0.009 89.4 83.0 −5.4 2.1 2.8 0.7 2.4 Δ None 9 0.05 88.2 87.2 −1.00.92 1.01 0.09 2.5 ◯ None 10 0.21 86.2 85.4 −0.8 0.65 0.71 0.06 3.2 ◯None 11 1.8 74.3 73.8 −0.5 0.63 0.62 −0.01 13.6 ◯ None 12 3.0 62.3 62.4+0.1 0.64 0.66 0.02 19.5 ◯ None Comparative 13 Ag—Nd 0.4 86.9 85.0 −1.90.52 0.61 0.09 4.9 X Observed Example 1 14 Ag—In 0.40 87.8 83.3 −4.5 3.67.1 3.5 4.5 Δ None 15 Ag—Nb 0.92 83.8 81.3 −2.5 2.1 3.1 1.0 9.5 ΔObserved 16 Ag—Sn 0.88 85.7 79.0 −6.7 3.5 6.2 2.7 6.4 X Observed NOTE:Discoloration (turning yellow): ◯: No discoloration, Δ: Slightdiscoloration, X: Large discoloration

TABLE 15 Evaluation results Reflectance (%): Wavelength 400 nm Initialreflectance Surface roughness (nm) Amount of before After Before Afterelement environ- environ- environ- environ- added mental mental Amountmental mental Amount Electric Test (at %) test test of change test testof change resistance No. Composition Bi, Sb Others [A] [B] [B − A] [C][D] [D − C] (μΩcm) Comparative 1 Pure Ag — — 90.8 63.5 −27.3 4.2 7.3 3.12.3 Example 2 4 Ag—Bi 0.19 — 86.2 85.4 −0.8 0.65 0.71 0.06 3.3 17Ag—Bi—Nd 0.19 0.7 85.1 84.7 −0.4 0.48 0.49 0.01 Not measured 18 Ag—Bi—Y0.19 0.5 85.4 84.8 −0.6 0.59 0.56 −0.03 Not measured 19 Ag—Bi—Cu 0.190.9 86.0 85.5 −0.5 0.68 0.70 0.02 3.4 20 Ag—Bi—Au 0.19 1.0 85.9 85.7−0.2 0.70 0.71 0.01 3.5 21 Ag—Bi—Cu 0.19 3.0 87.5 87.2 −0.3 0.63 0.720.09 4.1 22 Ag—Sb—Au 0.20 1.0 86.1 86.0 −0.1 0.65 0.68 0.03 3.2 23Ag—Sb—Cu 0.20 1.0 85.8 85.8 0.0 0.64 0.70 0.06 3.4 24 Ag—Sb—Cu 0.20 3.085.1 85.1 0.0 0.59 0.62 0.03 3.8

TABLE 16 Sample No. Composition of sputtering target Bi content of thinfilm 1 Ag—0.01at % Bi Alloy <0.001 2 Ag—0.04at % Bi Alloy <0.001 3Ag—0.05at % Bi Alloy 0.005 4 Ag—0.20at % Bi Alloy 0.011 5 Ag—1.41at % BiAlloy 0.056 6 Ag—4.50at % Bi Alloy 0.398 7 Ag—7.00at % Bi Alloy 1.02 8Ag—14.3at % Bi Alloy 3.82 9 Ag—22.9at % Bi Alloy 9.93 10 Ag—40.8at % BiAlloy 27.2

1. An optical information recording medium, comprising: a substratelayer, a reflective coating on the substrate layer, wherein thereflective coating comprises a silver base alloy containing 0.005 to 5at % bismuth, wherein the reflective coating has a thickness of at most20 nm, and wherein the bismuth is concentrated in the outer most surfaceof the reflective coating.
 2. The optical information recording mediumof claim 1, wherein the concentrated bismuth in the outermost surface ofthe first reflective coating forms an oxide.
 3. The optical informationrecording medium of claim 1, wherein the silver base alloy furthercomprises at least one rare earth metal element.
 4. The opticalinformation recording medium of claim 3, wherein the rare earth metalelement is Nd.
 5. The optical information recording medium of claim 3,wherein a total content of rare earth metal element is 0.1 to 2 at %. 6.The optical information recording medium of claim 1, wherein the silverbase alloy further comprises at least one element selected from Cu, Au,Rh, Pd, and Pt in an amount of 0.1 to 3 at %.
 7. The optical informationrecording medium of claim 1, wherein the reflective coating has athickness of 5 to 20 nm.
 8. The optical information recording medium ofclaim 1, wherein the silver base alloy contains 0.005 to 3 at % ofbismuth.
 9. An optical information recording medium, comprising: asubstrate layer, a reflective coating on the substrate layer, whereinthe reflective coating comprises a silver base alloy containing 0.005 to5 at % bismuth, and wherein the bismuth is concentrated in the outermost surface of the reflective coating.
 10. The optical informationrecording medium of claim 9, wherein the concentrated bismuth in theoutermost surface of the reflective coating forms an oxide.
 11. Theoptical information recording medium of claim 9, wherein the silver basealloy further comprises at least one rare earth metal element.
 12. Theoptical information recording medium of claim 11, wherein the rare earthmetal element is Nd.
 13. The optical information recording medium ofclaim 11, wherein a total content of rare earth metal element is 0.1 to2 at %.
 14. The optical information recording medium of claim 9, whereinthe silver base alloy further comprises at least one element selectedfrom Cu, Au, Rh, Pd, and Pt in an amount of 0.1 to 3 at %.
 15. Theoptical information recording medium of claim 9, wherein the reflectivecoating is high reflective.
 16. The optical information recording mediumof claim 9, wherein the reflective coating is a semi-transmissive film.17. An optical information recording medium, comprising: a substratelayer, a reflective coating on the substrate layer, wherein thereflective coating comprises a silver base alloy containing 0.005 to 5at % of bismuth, and wherein the bismuth in the outermost surface of thereflective coating forms an oxide.
 18. The optical information recordingmedium of claim 17, wherein the silver base alloy further comprises atleast one rare earth metal element.
 19. The optical informationrecording medium of claim 18, wherein the rare earth metal element isNd.
 20. The optical information recording medium of claim 18, wherein atotal content of rare earth metal element is 0.1 to 2 at %.
 21. Theoptical information recording medium of claim 17, wherein the silverbase alloy further comprises at least one element selected from Cu, Au,Rh, Pd, and Pt in an amount of 0.1 to 3 at %.
 22. The opticalinformation recording medium of claim 17, wherein the reflective coatingis high reflective.
 23. The optical information recording medium ofclaim 17, wherein the reflective coating is a semi-transmissive film.